Metalliferous mineralisation, Grampian Highlands - Revision history

Dbk at 15:42, 31 January 2018

2018-01-31T15:42:54Z

← Older revision		Revision as of 16:42, 31 January 2018
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	'''From: Stephenson, D, and Gould, D. 1995. [[British regional geology: Grampian Highlands\|British regional geology: Grampian Highlands.]] Fourth edition. Keyworth, Nottingham: British Geological Survey.'''		{{GHRG}}
	== Metalliferous mineralisation - introduction==		== Metalliferous mineralisation - introduction==
	Many occurrences of precious and base metals and of baryte have been discovered in the Grampian Highlands over the last quarter of a century as geochemical and other modern exploration techniques have been applied to the region; these add to the old records of metalliferous mineralisation (Wilson and Flett, 1921). Publications arising from the BGS Mineral Reconnaissance and Geochemical Survey programmes, plus the reports of exploration companies now on open file (Colman, 1990), form a metalliferous database comparable with that of any other region of similar size in the world. Geochemical atlases covering the Grampians record well over 100 locations of significant mineralisation (e.g. Gallagher, 1990; 1991a; Gallagher and Young, 1993) and provide multi-element data on drainage samples from 47 000 sites at a mean density of one sample/1.5 km<sup>2</sup>. Also available are comprehensive gravity and aeromagnetic maps; airborne electromagnetic and radiometric surveys of some areas have been placed on open file by exploration companies.		Many occurrences of precious and base metals and of baryte have been discovered in the Grampian Highlands over the last quarter of a century as geochemical and other modern exploration techniques have been applied to the region; these add to the old records of metalliferous mineralisation (Wilson and Flett, 1921). Publications arising from the BGS Mineral Reconnaissance and Geochemical Survey programmes, plus the reports of exploration companies now on open file (Colman, 1990), form a metalliferous database comparable with that of any other region of similar size in the world. Geochemical atlases covering the Grampians record well over 100 locations of significant mineralisation (e.g. Gallagher, 1990; 1991a; Gallagher and Young, 1993) and provide multi-element data on drainage samples from 47 000 sites at a mean density of one sample/1.5 km<sup>2</sup>. Also available are comprehensive gravity and aeromagnetic maps; airborne electromagnetic and radiometric surveys of some areas have been placed on open file by exploration companies.

Dbk: /* Vein deposits */

2015-11-26T12:02:18Z

Vein deposits

← Older revision		Revision as of 13:02, 26 November 2015
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	East of Loch Tay, at Corrie Buie (19), an outlier of the Loch Tay Limestone on the inverted limb of the Tay Nappe is cut by narrow quartz-sulphide veins trending 160°. Silver-rich galena, minor sphalerite, chalcopyrite and iron sulphides, and rare native bismuth and gold occur in a gangue of quartz and lesser carbonate. Adits uncovered in recent gold exploration follow veins for at least 200 m. Precious metals are also reported from chalcopyrite-rich ore mined from a quartz-calcite vein trending north-west in a metabasaltic body in Argyll Group rocks at Kilmartin (26).		East of Loch Tay, at Corrie Buie (19), an outlier of the Loch Tay Limestone on the inverted limb of the Tay Nappe is cut by narrow quartz-sulphide veins trending 160°. Silver-rich galena, minor sphalerite, chalcopyrite and iron sulphides, and rare native bismuth and gold occur in a gangue of quartz and lesser carbonate. Adits uncovered in recent gold exploration follow veins for at least 200 m. Precious metals are also reported from chalcopyrite-rich ore mined from a quartz-calcite vein trending north-west in a metabasaltic body in Argyll Group rocks at Kilmartin (26).

	Gold-bearing structures at Calliachar Burn south-west of Aberfeldy (15) trend 150° in garnetiferous mica-schist, psammitic schist and hornblende-schist of the Southern Highland Group. Although thin (0.1–0.5 m), the structures can contain up to 350 g/t Au, including visible gold in quartz veinlets and in goethite. Mineralisation was accompanied by movement on the structures, resulting in deformation of the sulphides. Hornblende-schist wallrocks are bleached over a few centimetres with formation of ferroan dolomite. In the hypogene sulphide assemblage ~~([[Media:P915456.jpg\|P915456]])~~, electrum (50–65 wt% Au) forms clusters of inclusions on fractures in pyrite and larger grains at pyrite–galena boundaries. Sphalerite is replaced in part by chalcopyrite. At surface, pyrite is oxidised to goethite, limonite and jarosite, and galena to anglesite and pyromorphite. Chalcopyrite breaks down to covellite and native copper, and arsenopyrite to scorodite. The nearby Urlar Burn veins (Wilson and Flett, 1921) are also NW-trending, at right angles to the regional Caledonide grain. Galena from the veins contains the tellurides altaite, hessite and coloradoite.		Gold-bearing structures at Calliachar Burn south-west of Aberfeldy (15) trend 150° in garnetiferous mica-schist, psammitic schist and hornblende-schist of the Southern Highland Group. Although thin (0.1–0.5 m), the structures can contain up to 350 g/t Au, including visible gold in quartz veinlets and in goethite. Mineralisation was accompanied by movement on the structures, resulting in deformation of the sulphides. Hornblende-schist wallrocks are bleached over a few centimetres with formation of ferroan dolomite. In the hypogene sulphide assemblage, electrum (50–65 wt% Au) forms clusters of inclusions on fractures in pyrite and larger grains at pyrite–galena boundaries. Sphalerite is replaced in part by chalcopyrite. At surface, pyrite is oxidised to goethite, limonite and jarosite, and galena to anglesite and pyromorphite. Chalcopyrite breaks down to covellite and native copper, and arsenopyrite to scorodite. The nearby Urlar Burn veins (Wilson and Flett, 1921) are also NW-trending, at right angles to the regional Caledonide grain. Galena from the veins contains the tellurides altaite, hessite and coloradoite.

	== Other types of mineralisation ==		== Other types of mineralisation ==

Dbk: /* Vein deposits */

2015-11-26T12:01:26Z

Vein deposits

← Older revision		Revision as of 13:01, 26 November 2015
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	East of Loch Tay, at Corrie Buie (19), an outlier of the Loch Tay Limestone on the inverted limb of the Tay Nappe is cut by narrow quartz-sulphide veins trending 160°. Silver-rich galena, minor sphalerite, chalcopyrite and iron sulphides, and rare native bismuth and gold occur in a gangue of quartz and lesser carbonate. Adits uncovered in recent gold exploration follow veins for at least 200 m. Precious metals are also reported from chalcopyrite-rich ore mined from a quartz-calcite vein trending north-west in a metabasaltic body in Argyll Group rocks at Kilmartin (26).		East of Loch Tay, at Corrie Buie (19), an outlier of the Loch Tay Limestone on the inverted limb of the Tay Nappe is cut by narrow quartz-sulphide veins trending 160°. Silver-rich galena, minor sphalerite, chalcopyrite and iron sulphides, and rare native bismuth and gold occur in a gangue of quartz and lesser carbonate. Adits uncovered in recent gold exploration follow veins for at least 200 m. Precious metals are also reported from chalcopyrite-rich ore mined from a quartz-calcite vein trending north-west in a metabasaltic body in Argyll Group rocks at Kilmartin (26).

	Gold-bearing structures at Calliachar Burn south-west of Aberfeldy (15) trend 150° in garnetiferous mica-schist, psammitic schist and hornblende-schist of the Southern Highland Group. Although thin (0.1–0.5 m), the structures can contain up to 350 g/t Au, including visible gold in quartz veinlets and in goethite. Mineralisation was accompanied by movement on the structures, resulting in deformation of the sulphides. Hornblende-schist wallrocks are bleached over a few centimetres with formation of ferroan dolomite. In the hypogene sulphide assemblage ([[Media:P915456.~~png~~\|P915456]]), electrum (50–65 wt% Au) forms clusters of inclusions on fractures in pyrite and larger grains at pyrite–galena boundaries. Sphalerite is replaced in part by chalcopyrite. At surface, pyrite is oxidised to goethite, limonite and jarosite, and galena to anglesite and pyromorphite. Chalcopyrite breaks down to covellite and native copper, and arsenopyrite to scorodite. The nearby Urlar Burn veins (Wilson and Flett, 1921) are also NW-trending, at right angles to the regional Caledonide grain. Galena from the veins contains the tellurides altaite, hessite and coloradoite.		Gold-bearing structures at Calliachar Burn south-west of Aberfeldy (15) trend 150° in garnetiferous mica-schist, psammitic schist and hornblende-schist of the Southern Highland Group. Although thin (0.1–0.5 m), the structures can contain up to 350 g/t Au, including visible gold in quartz veinlets and in goethite. Mineralisation was accompanied by movement on the structures, resulting in deformation of the sulphides. Hornblende-schist wallrocks are bleached over a few centimetres with formation of ferroan dolomite. In the hypogene sulphide assemblage ([[Media:P915456.jpg\|P915456]]), electrum (50–65 wt% Au) forms clusters of inclusions on fractures in pyrite and larger grains at pyrite–galena boundaries. Sphalerite is replaced in part by chalcopyrite. At surface, pyrite is oxidised to goethite, limonite and jarosite, and galena to anglesite and pyromorphite. Chalcopyrite breaks down to covellite and native copper, and arsenopyrite to scorodite. The nearby Urlar Burn veins (Wilson and Flett, 1921) are also NW-trending, at right angles to the regional Caledonide grain. Galena from the veins contains the tellurides altaite, hessite and coloradoite.

	== Other types of mineralisation ==		== Other types of mineralisation ==

Dbk: /* Vein deposits */

2015-11-26T12:00:52Z

Vein deposits

← Older revision		Revision as of 13:00, 26 November 2015
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	East of Loch Tay, at Corrie Buie (19), an outlier of the Loch Tay Limestone on the inverted limb of the Tay Nappe is cut by narrow quartz-sulphide veins trending 160°. Silver-rich galena, minor sphalerite, chalcopyrite and iron sulphides, and rare native bismuth and gold occur in a gangue of quartz and lesser carbonate. Adits uncovered in recent gold exploration follow veins for at least 200 m. Precious metals are also reported from chalcopyrite-rich ore mined from a quartz-calcite vein trending north-west in a metabasaltic body in Argyll Group rocks at Kilmartin (26).		East of Loch Tay, at Corrie Buie (19), an outlier of the Loch Tay Limestone on the inverted limb of the Tay Nappe is cut by narrow quartz-sulphide veins trending 160°. Silver-rich galena, minor sphalerite, chalcopyrite and iron sulphides, and rare native bismuth and gold occur in a gangue of quartz and lesser carbonate. Adits uncovered in recent gold exploration follow veins for at least 200 m. Precious metals are also reported from chalcopyrite-rich ore mined from a quartz-calcite vein trending north-west in a metabasaltic body in Argyll Group rocks at Kilmartin (26).

	Gold-bearing structures at Calliachar Burn south-west of Aberfeldy (15) trend 150° in garnetiferous mica-schist, psammitic schist and hornblende-schist of the Southern Highland Group. Although thin (0.1–0.5 m), the structures can contain up to 350 g/t Au, including visible gold in quartz veinlets and in goethite. Mineralisation was accompanied by movement on the structures, resulting in deformation of the sulphides. Hornblende-schist wallrocks are bleached over a few centimetres with formation of ferroan dolomite. In the hypogene sulphide assemblage (P915456), electrum (50–65 wt% Au) forms clusters of inclusions on fractures in pyrite and larger grains at pyrite–galena boundaries. Sphalerite is replaced in part by chalcopyrite. At surface, pyrite is oxidised to goethite, limonite and jarosite, and galena to anglesite and pyromorphite. Chalcopyrite breaks down to covellite and native copper, and arsenopyrite to scorodite. The nearby Urlar Burn veins (Wilson and Flett, 1921) are also NW-trending, at right angles to the regional Caledonide grain. Galena from the veins contains the tellurides altaite, hessite and coloradoite.		Gold-bearing structures at Calliachar Burn south-west of Aberfeldy (15) trend 150° in garnetiferous mica-schist, psammitic schist and hornblende-schist of the Southern Highland Group. Although thin (0.1–0.5 m), the structures can contain up to 350 g/t Au, including visible gold in quartz veinlets and in goethite. Mineralisation was accompanied by movement on the structures, resulting in deformation of the sulphides. Hornblende-schist wallrocks are bleached over a few centimetres with formation of ferroan dolomite. In the hypogene sulphide assemblage ([[Media:P915456.png\|P915456]]), electrum (50–65 wt% Au) forms clusters of inclusions on fractures in pyrite and larger grains at pyrite–galena boundaries. Sphalerite is replaced in part by chalcopyrite. At surface, pyrite is oxidised to goethite, limonite and jarosite, and galena to anglesite and pyromorphite. Chalcopyrite breaks down to covellite and native copper, and arsenopyrite to scorodite. The nearby Urlar Burn veins (Wilson and Flett, 1921) are also NW-trending, at right angles to the regional Caledonide grain. Galena from the veins contains the tellurides altaite, hessite and coloradoite.

	== Other types of mineralisation ==		== Other types of mineralisation ==

Dbk: /* Vein deposits */

2015-11-26T11:59:56Z

Vein deposits

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	The Cononish gold-silver vein is 0.2 to 6 m thick and has been proved over 0.7 km of strike-length and up to 0.5 km below surface within a fault structure traceable for 2.5 km. Ore reserves of 0.75 Mt grading 10 g/t Au and 43 g/t Ag have been defined. Quartz veins containing visible gold were first located at the near-surface intersection of the fault structure with the Ben Eagach Schist, lying above the much older metasedimentary rocks at a slide junction (Gallagher, 1991b, fig. 16.18). The fault trends 050°, terminating north-eastwards against a barren quartz vein, the Mother Reef. Pyrite is the dominant sulphide of the Cononish structure, occurring with fine-grained galena in an early phase of white quartz and in a later phase of mottled quartz formed as a result of brecciation. Gold occurs in the pyrite and galena, usually as particles less than 20 m in size. Chalcopyrite, sphalerite and minor amounts of haematite, covellite, tellurides and native silver are also present. Gold values are lower in a phase of grey pyritic quartz and absent from cross-cutting white quartz.		The Cononish gold-silver vein is 0.2 to 6 m thick and has been proved over 0.7 km of strike-length and up to 0.5 km below surface within a fault structure traceable for 2.5 km. Ore reserves of 0.75 Mt grading 10 g/t Au and 43 g/t Ag have been defined. Quartz veins containing visible gold were first located at the near-surface intersection of the fault structure with the Ben Eagach Schist, lying above the much older metasedimentary rocks at a slide junction (Gallagher, 1991b, fig. 16.18). The fault trends 050°, terminating north-eastwards against a barren quartz vein, the Mother Reef. Pyrite is the dominant sulphide of the Cononish structure, occurring with fine-grained galena in an early phase of white quartz and in a later phase of mottled quartz formed as a result of brecciation. Gold occurs in the pyrite and galena, usually as particles less than 20 m in size. Chalcopyrite, sphalerite and minor amounts of haematite, covellite, tellurides and native silver are also present. Gold values are lower in a phase of grey pyritic quartz and absent from cross-cutting white quartz.

	The Cononish gold vein is best developed where the fault intersects psammitic rocks, which display alteration up to 15 m from the vein contact. An outer chloritised zone is succeeded by a sericitised zone and, within 2 m of the vein, intensely altered and reddened psammite, which has been haematitised, silicified and pyritised, can carry economic gold values. The presence of red psammite clasts within the early phase of white quartz signifies alteration and brecciation of wallrock prior to vein formation. The gold-bearing structure is cut by a late Carboniferous basic dyke and by the Eas Anie Vein (P244649). This vein is characterised by coarse-grained galena, calcite and baryte with only minor pyrite; it is not gold-bearing, nor are the Hard and other veins mined for lead in the past.		The Cononish gold vein is best developed where the fault intersects psammitic rocks, which display alteration up to 15 m from the vein contact. An outer chloritised zone is succeeded by a sericitised zone and, within 2 m of the vein, intensely altered and reddened psammite, which has been haematitised, silicified and pyritised, can carry economic gold values. The presence of red psammite clasts within the early phase of white quartz signifies alteration and brecciation of wallrock prior to vein formation. The gold-bearing structure is cut by a late Carboniferous basic dyke and by the Eas Anie Vein ([[Media:P244649.jpg\|P244649]]). This vein is characterised by coarse-grained galena, calcite and baryte with only minor pyrite; it is not gold-bearing, nor are the Hard and other veins mined for lead in the past.

	At Tyndrum Mine ''(21)'' the Hard Vein dips steeply south-east to terminate against the Tyndrum Fault, occupied by the later Clay Vein. Levels 145 to 365 m in length were driven through 230 m of vertical interval along veins up to 6 m thick containing coarse-grained galena and sphalerite, together with chalcopyrite and a little pyrite. Massive quartz is the main gangue mineral, accompanied by local concentrations of calcite and baryte. Ore textures are typical of growth into ‘open space’, namely vuggy breccias and banded veins. Silver-and cadmium-rich tetrahedrites occur in the massive galena. Minor amounts of uraninite have been recorded from a cross-course vein.		At Tyndrum Mine ''(21)'' the Hard Vein dips steeply south-east to terminate against the Tyndrum Fault, occupied by the later Clay Vein. Levels 145 to 365 m in length were driven through 230 m of vertical interval along veins up to 6 m thick containing coarse-grained galena and sphalerite, together with chalcopyrite and a little pyrite. Massive quartz is the main gangue mineral, accompanied by local concentrations of calcite and baryte. Ore textures are typical of growth into ‘open space’, namely vuggy breccias and banded veins. Silver-and cadmium-rich tetrahedrites occur in the massive galena. Minor amounts of uraninite have been recorded from a cross-course vein.

Dbk: /* Mineral production */

2015-11-26T11:58:18Z

Mineral production

← Older revision		Revision as of 12:58, 26 November 2015
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	Mining for lead, with silver as a valuable by-product, and to a lesser extent for copper, nickel and manganese, was quite widespread in the Grampian Highlands in the past, extending into the present century only at Tyndrum (21 on [[Media:P915451.png\|P915451]]) where about 10 000 tonnes of lead ore were produced from veins in the periods 1741 to 1862 and 1916 to 1925. Some 200 t of zinc ore was extracted from dumps in this final period. Wilson and Flett (1921) record an output of 1400 t lead and 0.5 t silver in the period 1862 to 1880 from Islay, principally from veins at Mulreesh (28). Smaller mines at Abergairn (9) and Corrie Buie (19) exploited lead veins and the Kilmartin veins (26) yielded copper, as did a diorite-granite intrusion containing disseminated sulphides at Tomnadashan (17). Some 400 t of ore containing nickeliferous pyrrhotite were raised from the Coillebraghad deposit (24) which, like the old copper mine of Abhainn Strathain at Meall Mor (27) and the lead-copper trial at McPhun’s Cairn (25), is classified as Dalradian stratabound in type. Iron was extracted in the eighteenth century, and manganese in the nineteenth, from breccias in the Dalradian at the Lecht (7).		Mining for lead, with silver as a valuable by-product, and to a lesser extent for copper, nickel and manganese, was quite widespread in the Grampian Highlands in the past, extending into the present century only at Tyndrum (21 on [[Media:P915451.png\|P915451]]) where about 10 000 tonnes of lead ore were produced from veins in the periods 1741 to 1862 and 1916 to 1925. Some 200 t of zinc ore was extracted from dumps in this final period. Wilson and Flett (1921) record an output of 1400 t lead and 0.5 t silver in the period 1862 to 1880 from Islay, principally from veins at Mulreesh (28). Smaller mines at Abergairn (9) and Corrie Buie (19) exploited lead veins and the Kilmartin veins (26) yielded copper, as did a diorite-granite intrusion containing disseminated sulphides at Tomnadashan (17). Some 400 t of ore containing nickeliferous pyrrhotite were raised from the Coillebraghad deposit (24) which, like the old copper mine of Abhainn Strathain at Meall Mor (27) and the lead-copper trial at McPhun’s Cairn (25), is classified as Dalradian stratabound in type. Iron was extracted in the eighteenth century, and manganese in the nineteenth, from breccias in the Dalradian at the Lecht (7).

	Bedded baryte and zinc-lead sulphide deposits in Dalradian rocks of the Aberfeldy district, found in the 1970s (Coats et al., 1984) are among the most important mineral discoveries to be made in Britain this century. Foss Mine (13), the largest baryte producer in Britain, and the Ben Eagach Quarry (12; [[Media:P064564.~~png~~\|P064564]]) have yielded more than 0.5 Mt of direct shipping-grade ore (defined by a minimum specific gravity of 4.2 gcm<sup>-3</sup>) since 1984 for use in drilling fluid in North Sea hydrocarbons operations. Underground production of 0.2 Mt/annum over 30 years is planned for the adjacent Duntanlich deposit (11) (Butcher et al., 1991). A small amount of baryte was quarried at Balfriesh (3) around 1980. Economic evaluations have also taken place of gold-bearing structures at Cononish (22), presently regarded as Britain’s premier gold-silver deposit, and at Calliachar Burn (15) where a little gold was extracted in 1991.		Bedded baryte and zinc-lead sulphide deposits in Dalradian rocks of the Aberfeldy district, found in the 1970s (Coats et al., 1984) are among the most important mineral discoveries to be made in Britain this century. Foss Mine (13), the largest baryte producer in Britain, and the Ben Eagach Quarry (12; [[Media:P064564.jpg\|P064564]]) have yielded more than 0.5 Mt of direct shipping-grade ore (defined by a minimum specific gravity of 4.2 gcm<sup>-3</sup>) since 1984 for use in drilling fluid in North Sea hydrocarbons operations. Underground production of 0.2 Mt/annum over 30 years is planned for the adjacent Duntanlich deposit (11) (Butcher et al., 1991). A small amount of baryte was quarried at Balfriesh (3) around 1980. Economic evaluations have also taken place of gold-bearing structures at Cononish (22), presently regarded as Britain’s premier gold-silver deposit, and at Calliachar Burn (15) where a little gold was extracted in 1991.

	== Dalradian stratabound mineralisation ==		== Dalradian stratabound mineralisation ==

Dbk: /* Mineral production */

2015-11-26T11:57:56Z

Mineral production

← Older revision		Revision as of 12:57, 26 November 2015
Line 94:		Line 94:
	Mining for lead, with silver as a valuable by-product, and to a lesser extent for copper, nickel and manganese, was quite widespread in the Grampian Highlands in the past, extending into the present century only at Tyndrum (21 on [[Media:P915451.png\|P915451]]) where about 10 000 tonnes of lead ore were produced from veins in the periods 1741 to 1862 and 1916 to 1925. Some 200 t of zinc ore was extracted from dumps in this final period. Wilson and Flett (1921) record an output of 1400 t lead and 0.5 t silver in the period 1862 to 1880 from Islay, principally from veins at Mulreesh (28). Smaller mines at Abergairn (9) and Corrie Buie (19) exploited lead veins and the Kilmartin veins (26) yielded copper, as did a diorite-granite intrusion containing disseminated sulphides at Tomnadashan (17). Some 400 t of ore containing nickeliferous pyrrhotite were raised from the Coillebraghad deposit (24) which, like the old copper mine of Abhainn Strathain at Meall Mor (27) and the lead-copper trial at McPhun’s Cairn (25), is classified as Dalradian stratabound in type. Iron was extracted in the eighteenth century, and manganese in the nineteenth, from breccias in the Dalradian at the Lecht (7).		Mining for lead, with silver as a valuable by-product, and to a lesser extent for copper, nickel and manganese, was quite widespread in the Grampian Highlands in the past, extending into the present century only at Tyndrum (21 on [[Media:P915451.png\|P915451]]) where about 10 000 tonnes of lead ore were produced from veins in the periods 1741 to 1862 and 1916 to 1925. Some 200 t of zinc ore was extracted from dumps in this final period. Wilson and Flett (1921) record an output of 1400 t lead and 0.5 t silver in the period 1862 to 1880 from Islay, principally from veins at Mulreesh (28). Smaller mines at Abergairn (9) and Corrie Buie (19) exploited lead veins and the Kilmartin veins (26) yielded copper, as did a diorite-granite intrusion containing disseminated sulphides at Tomnadashan (17). Some 400 t of ore containing nickeliferous pyrrhotite were raised from the Coillebraghad deposit (24) which, like the old copper mine of Abhainn Strathain at Meall Mor (27) and the lead-copper trial at McPhun’s Cairn (25), is classified as Dalradian stratabound in type. Iron was extracted in the eighteenth century, and manganese in the nineteenth, from breccias in the Dalradian at the Lecht (7).

	Bedded baryte and zinc-lead sulphide deposits in Dalradian rocks of the Aberfeldy district, found in the 1970s (Coats et al., 1984) are among the most important mineral discoveries to be made in Britain this century. Foss Mine (13), the largest baryte producer in Britain, and the Ben Eagach Quarry (12~~<nowiki>~~; [[Media:P064564.png\|P064564]]) have yielded more than 0.5 Mt of direct shipping-grade ore (defined by a minimum specific gravity of 4.2 gcm~~</nowiki>~~<sup>-3</sup>) since 1984 for use in drilling fluid in North Sea hydrocarbons operations. Underground production of 0.2 Mt/annum over 30 years is planned for the adjacent Duntanlich deposit (11) (Butcher et al., 1991). A small amount of baryte was quarried at Balfriesh (3) around 1980. Economic evaluations have also taken place of gold-bearing structures at Cononish (22), presently regarded as Britain’s premier gold-silver deposit, and at Calliachar Burn (15) where a little gold was extracted in 1991.		Bedded baryte and zinc-lead sulphide deposits in Dalradian rocks of the Aberfeldy district, found in the 1970s (Coats et al., 1984) are among the most important mineral discoveries to be made in Britain this century. Foss Mine (13), the largest baryte producer in Britain, and the Ben Eagach Quarry (12; [[Media:P064564.png\|P064564]]) have yielded more than 0.5 Mt of direct shipping-grade ore (defined by a minimum specific gravity of 4.2 gcm<sup>-3</sup>) since 1984 for use in drilling fluid in North Sea hydrocarbons operations. Underground production of 0.2 Mt/annum over 30 years is planned for the adjacent Duntanlich deposit (11) (Butcher et al., 1991). A small amount of baryte was quarried at Balfriesh (3) around 1980. Economic evaluations have also taken place of gold-bearing structures at Cononish (22), presently regarded as Britain’s premier gold-silver deposit, and at Calliachar Burn (15) where a little gold was extracted in 1991.

	== Dalradian stratabound mineralisation ==		== Dalradian stratabound mineralisation ==

Dbk: /* Mineral production */

2015-11-26T11:57:17Z

Mineral production

← Older revision		Revision as of 12:57, 26 November 2015
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	Mining for lead, with silver as a valuable by-product, and to a lesser extent for copper, nickel and manganese, was quite widespread in the Grampian Highlands in the past, extending into the present century only at Tyndrum (21 on [[Media:P915451.png\|P915451]]) where about 10 000 tonnes of lead ore were produced from veins in the periods 1741 to 1862 and 1916 to 1925. Some 200 t of zinc ore was extracted from dumps in this final period. Wilson and Flett (1921) record an output of 1400 t lead and 0.5 t silver in the period 1862 to 1880 from Islay, principally from veins at Mulreesh (28). Smaller mines at Abergairn (9) and Corrie Buie (19) exploited lead veins and the Kilmartin veins (26) yielded copper, as did a diorite-granite intrusion containing disseminated sulphides at Tomnadashan (17). Some 400 t of ore containing nickeliferous pyrrhotite were raised from the Coillebraghad deposit (24) which, like the old copper mine of Abhainn Strathain at Meall Mor (27) and the lead-copper trial at McPhun’s Cairn (25), is classified as Dalradian stratabound in type. Iron was extracted in the eighteenth century, and manganese in the nineteenth, from breccias in the Dalradian at the Lecht (7).		Mining for lead, with silver as a valuable by-product, and to a lesser extent for copper, nickel and manganese, was quite widespread in the Grampian Highlands in the past, extending into the present century only at Tyndrum (21 on [[Media:P915451.png\|P915451]]) where about 10 000 tonnes of lead ore were produced from veins in the periods 1741 to 1862 and 1916 to 1925. Some 200 t of zinc ore was extracted from dumps in this final period. Wilson and Flett (1921) record an output of 1400 t lead and 0.5 t silver in the period 1862 to 1880 from Islay, principally from veins at Mulreesh (28). Smaller mines at Abergairn (9) and Corrie Buie (19) exploited lead veins and the Kilmartin veins (26) yielded copper, as did a diorite-granite intrusion containing disseminated sulphides at Tomnadashan (17). Some 400 t of ore containing nickeliferous pyrrhotite were raised from the Coillebraghad deposit (24) which, like the old copper mine of Abhainn Strathain at Meall Mor (27) and the lead-copper trial at McPhun’s Cairn (25), is classified as Dalradian stratabound in type. Iron was extracted in the eighteenth century, and manganese in the nineteenth, from breccias in the Dalradian at the Lecht (7).

	Bedded baryte and zinc-lead sulphide deposits in Dalradian rocks of the Aberfeldy district, found in the 1970s (Coats et al., 1984) are among the most important mineral discoveries to be made in Britain this century. Foss Mine (13), the largest baryte producer in Britain, and the Ben Eagach Quarry (12<nowiki>; P064564) have yielded more than 0.5 Mt of direct shipping-grade ore (defined by a minimum specific gravity of 4.2 gcm</nowiki><sup>-3</sup>) since 1984 for use in drilling fluid in North Sea hydrocarbons operations. Underground production of 0.2 Mt/annum over 30 years is planned for the adjacent Duntanlich deposit (11) (Butcher et al., 1991). A small amount of baryte was quarried at Balfriesh (3) around 1980. Economic evaluations have also taken place of gold-bearing structures at Cononish (22), presently regarded as Britain’s premier gold-silver deposit, and at Calliachar Burn (15) where a little gold was extracted in 1991.		Bedded baryte and zinc-lead sulphide deposits in Dalradian rocks of the Aberfeldy district, found in the 1970s (Coats et al., 1984) are among the most important mineral discoveries to be made in Britain this century. Foss Mine (13), the largest baryte producer in Britain, and the Ben Eagach Quarry (12<nowiki>; [[Media:P064564.png\|P064564]]) have yielded more than 0.5 Mt of direct shipping-grade ore (defined by a minimum specific gravity of 4.2 gcm</nowiki><sup>-3</sup>) since 1984 for use in drilling fluid in North Sea hydrocarbons operations. Underground production of 0.2 Mt/annum over 30 years is planned for the adjacent Duntanlich deposit (11) (Butcher et al., 1991). A small amount of baryte was quarried at Balfriesh (3) around 1980. Economic evaluations have also taken place of gold-bearing structures at Cononish (22), presently regarded as Britain’s premier gold-silver deposit, and at Calliachar Burn (15) where a little gold was extracted in 1991.

	== Dalradian stratabound mineralisation ==		== Dalradian stratabound mineralisation ==

Dbk: /* Mineral production */

2015-11-26T11:56:29Z

Mineral production

← Older revision		Revision as of 12:56, 26 November 2015
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	== Mineral production ==		== Mineral production ==
	Mining for lead, with silver as a valuable by-product, and to a lesser extent for copper, nickel and manganese, was quite widespread in the Grampian Highlands in the past, extending into the present century only at Tyndrum (21 on P915451) where about 10 000 tonnes of lead ore were produced from veins in the periods 1741 to 1862 and 1916 to 1925. Some 200 t of zinc ore was extracted from dumps in this final period. Wilson and Flett (1921) record an output of 1400 t lead and 0.5 t silver in the period 1862 to 1880 from Islay, principally from veins at Mulreesh (28). Smaller mines at Abergairn (9) and Corrie Buie (19) exploited lead veins and the Kilmartin veins (26) yielded copper, as did a diorite-granite intrusion containing disseminated sulphides at Tomnadashan (17). Some 400 t of ore containing nickeliferous pyrrhotite were raised from the Coillebraghad deposit (24) which, like the old copper mine of Abhainn Strathain at Meall Mor (27) and the lead-copper trial at McPhun’s Cairn (25), is classified as Dalradian stratabound in type. Iron was extracted in the eighteenth century, and manganese in the nineteenth, from breccias in the Dalradian at the Lecht (7).		Mining for lead, with silver as a valuable by-product, and to a lesser extent for copper, nickel and manganese, was quite widespread in the Grampian Highlands in the past, extending into the present century only at Tyndrum (21 on [[Media:P915451.png\|P915451]]) where about 10 000 tonnes of lead ore were produced from veins in the periods 1741 to 1862 and 1916 to 1925. Some 200 t of zinc ore was extracted from dumps in this final period. Wilson and Flett (1921) record an output of 1400 t lead and 0.5 t silver in the period 1862 to 1880 from Islay, principally from veins at Mulreesh (28). Smaller mines at Abergairn (9) and Corrie Buie (19) exploited lead veins and the Kilmartin veins (26) yielded copper, as did a diorite-granite intrusion containing disseminated sulphides at Tomnadashan (17). Some 400 t of ore containing nickeliferous pyrrhotite were raised from the Coillebraghad deposit (24) which, like the old copper mine of Abhainn Strathain at Meall Mor (27) and the lead-copper trial at McPhun’s Cairn (25), is classified as Dalradian stratabound in type. Iron was extracted in the eighteenth century, and manganese in the nineteenth, from breccias in the Dalradian at the Lecht (7).

	Bedded baryte and zinc-lead sulphide deposits in Dalradian rocks of the Aberfeldy district, found in the 1970s (Coats et al., 1984) are among the most important mineral discoveries to be made in Britain this century. Foss Mine (13), the largest baryte producer in Britain, and the Ben Eagach Quarry (12<nowiki>; P064564) have yielded more than 0.5 Mt of direct shipping-grade ore (defined by a minimum specific gravity of 4.2 gcm</nowiki><sup>-3</sup>) since 1984 for use in drilling fluid in North Sea hydrocarbons operations. Underground production of 0.2 Mt/annum over 30 years is planned for the adjacent Duntanlich deposit (11) (Butcher et al., 1991). A small amount of baryte was quarried at Balfriesh (3) around 1980. Economic evaluations have also taken place of gold-bearing structures at Cononish (22), presently regarded as Britain’s premier gold-silver deposit, and at Calliachar Burn (15) where a little gold was extracted in 1991.		Bedded baryte and zinc-lead sulphide deposits in Dalradian rocks of the Aberfeldy district, found in the 1970s (Coats et al., 1984) are among the most important mineral discoveries to be made in Britain this century. Foss Mine (13), the largest baryte producer in Britain, and the Ben Eagach Quarry (12<nowiki>; P064564) have yielded more than 0.5 Mt of direct shipping-grade ore (defined by a minimum specific gravity of 4.2 gcm</nowiki><sup>-3</sup>) since 1984 for use in drilling fluid in North Sea hydrocarbons operations. Underground production of 0.2 Mt/annum over 30 years is planned for the adjacent Duntanlich deposit (11) (Butcher et al., 1991). A small amount of baryte was quarried at Balfriesh (3) around 1980. Economic evaluations have also taken place of gold-bearing structures at Cononish (22), presently regarded as Britain’s premier gold-silver deposit, and at Calliachar Burn (15) where a little gold was extracted in 1991.

Scotfot at 18:28, 27 July 2015

2015-07-27T18:28:01Z

← Older revision		Revision as of 19:28, 27 July 2015
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	== Dalradian stratabound mineralisation ==		== Dalradian stratabound mineralisation ==
	[[File:P915451.png\|thumbnail\|P915451]]		[[File:P915451.png\|thumbnail\|Principal metalliferous mineral occurrences in the Grampian Highlands. P915451.]]
	[[File:P064564.jpg\|thumbnail\|P064564]]		[[File:P064564.jpg\|thumbnail\|Stratabound baryte deposit, Ben Eagach Quarry, Aberfeldy, Perthshire. P064564.]]
	[[File:P244649.jpg\|thumbnail\|P244649]]		[[File:P244649.jpg\|thumbnail\|Eas Anie Vein, Cononish gold prospect, Tyndrum, Perthshire; a complex breccia vein (right) cut by shears (centre). P244649.]]
	Metasedimentary rocks of the Easdale and Crinan subgroups in the Argyll Group contain stratabound deposits of baryte, barium silicates, base metal sulphides and chromian minerals at locations over some 200 km of the regional strike [[Media:P915448.png\|(P915448)]]. Mineralisation is recognisable in at least six horizons despite Caledonian deformation and amphibolite-grade metamorphism (Smith et al., 1984).		Metasedimentary rocks of the Easdale and Crinan subgroups in the Argyll Group contain stratabound deposits of baryte, barium silicates, base metal sulphides and chromian minerals at locations over some 200 km of the regional strike [[Media:P915448.png\|(P915448)]]. Mineralisation is recognisable in at least six horizons despite Caledonian deformation and amphibolite-grade metamorphism (Smith et al., 1984).

← Older revision		Revision as of 19:28, 27 July 2015
Line 97:		Line 97:

	== Dalradian stratabound mineralisation ==		== Dalradian stratabound mineralisation ==
	[[File:P915451.png\|thumbnail\|P915451]]		[[File:P915451.png\|thumbnail\|Principal metalliferous mineral occurrences in the Grampian Highlands. P915451.]]
	[[File:P064564.jpg\|thumbnail\|P064564]]		[[File:P064564.jpg\|thumbnail\|Stratabound baryte deposit, Ben Eagach Quarry, Aberfeldy, Perthshire. P064564.]]
	[[File:P244649.jpg\|thumbnail\|P244649]]		[[File:P244649.jpg\|thumbnail\|Eas Anie Vein, Cononish gold prospect, Tyndrum, Perthshire; a complex breccia vein (right) cut by shears (centre). P244649.]]
	Metasedimentary rocks of the Easdale and Crinan subgroups in the Argyll Group contain stratabound deposits of baryte, barium silicates, base metal sulphides and chromian minerals at locations over some 200 km of the regional strike [[Media:P915448.png\|(P915448)]]. Mineralisation is recognisable in at least six horizons despite Caledonian deformation and amphibolite-grade metamorphism (Smith et al., 1984).		Metasedimentary rocks of the Easdale and Crinan subgroups in the Argyll Group contain stratabound deposits of baryte, barium silicates, base metal sulphides and chromian minerals at locations over some 200 km of the regional strike [[Media:P915448.png\|(P915448)]]. Mineralisation is recognisable in at least six horizons despite Caledonian deformation and amphibolite-grade metamorphism (Smith et al., 1984).