OR/13/015 Appendix 6 - Petrographic descriptions of Falkirk building stones

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Gillespie, M R, Everett, P A, Albornoz-Parra, L J, and Tracey, E A. 2013. A survey of building stone and roofing slate in Falkirk town centre. Nottingham, UK, British geological Survey. (OR/13/015).

This appendix contains petrographic descriptions for nineteen samples of stone collected from Falkirk; see section 5.3 and Table 7 for sample details. Each description is presented on a Petrographic Description Form designed for sandstone. Two photographs of the stone as it appears in thin section (viewed using an optical microscope) accompany the descriptions of the twelve samples for which a thin section was prepared. A page of notes at the end of this appendix describes each property recorded on the forms.

BGS sample number: ED11047
PRIMARY_KE: 963250
Building stone: Buff sandstone 4
Sample dimensions: 130 x 40 x 35 mm
Building address: 30 Newmarket Street

Hand specimen observations
Stone type1 (general classification): sandstone
Stone colour2 – fresh stone: light buff
Stone colour2 – weathered stone: orangeish buff
Stone colour2 – exterior surface: greyish buff
Stone cohesion3 – fresh stone: strongly cohesive
Stone cohesion3 – weathered stone: strongly cohesive
Primary sedimentary structure4: uniform (some orientated grains)
Distinctive features5: speckled
Reaction to 10% HCl6: moderate
Water absorption (permeability)7: high

Thin section observations

Stone constituents 8: Granular (detrital) constituents Intergranular constituents Quartz 57% Silica (overgrowth) 2% Feldspar 3% Feldspar (overgrowth) <1% Rock fragments 2% Carbonate 3% Mica 1% Iron/manganese oxide 1% Opaque material <1% Clay 10% Other <<1% Hydrocarbon 0% Intragranular pores 2% Intergranular pores 18% Stone type 1 (detailed classification): subfeldspathic-arenite Grain-size 9: fine-sand-grade to medium-sand-grade Grain sorting 10: moderately well sorted Grain roundness 11: sub-angular to sub-rounded Cement distribution 12: silica cement continuous; carbonate cement isolated Supergene changes 13: moderate dissolution of feldspar

Comments 1) The sample consists of a chip from a window dressing.

2) The exterior surface is weathered to a depth of less than 1 mm.

3) The speckles are mainly black and evenly scattered. Some are pale orangeish brown.

4) The exterior surface is weathered to a maximum depth of 4 mm.

5) Tourmaline and rounded grains of zircon appear as accessory minerals.

6) The stone contains rare, scattered grains of coarse-sand grade.

7) Iron oxide rims on carbonate crystals suggest the carbonate mineral is ferroan (ferroan dolomite, ankerite or siderite).





Figure A6_1. Two images of sample ED11047, as it appears in thin section. White grains are mainly quartz. Black areas are mainly iron oxide minerals. Dark mottled patches are carbonate mineral. Pore spaces appear blue. The field of view is 3.3 mm wide.


BGS sample number: ED11048-1 Sample dimensions: 110 x 80 x 30 mm PRIMARY_KE: 963306 Building address: Burgh Buildings Building stone: Buff sandstone 1


Hand specimen observations Stone type 1 (general classification): sandstone Stone colour 2 – fresh stone: buff Stone colour 2 – weathered stone: buff Stone colour 2 – exterior surface: buff to greenish buff Stone cohesion 3 – fresh stone: strongly cohesive Stone cohesion 3 – weathered stone: moderately cohesive Primary sedimentary structure 4: parallel lamination Distinctive features 5: faintly speckled; carbonaceous matter Reaction to 10% HCl 6: none Water absorption (permeability) 7: high

Thin section observations

Stone constituents 8: Granular (detrital) constituents Intergranular constituents Quartz 45% Silica (overgrowth) 4% Feldspar 3% Feldspar (overgrowth) 0% Rock fragments 1% Carbonate 7% Mica <1% Iron/manganese oxide 7% Opaque material <1% Clay 12% Other <1% Hydrocarbon 0% Intragranular pores 3% Intergranular pores 17% Stone type 1 (detailed classification): subfeldspathic-arenite Grain-size 9: fine-sand-grade to medium-sand-grade Grain sorting 10: moderately well sorted Grain roundness 11: sub-angular to well rounded Cement distribution 12: silica cement continuous; carbonate cement isolated Supergene changes 13: moderate dissolution of feldspar


Comments 1) The sample is a chip from rock faced walling at low level on the front elevation.

2) The exterior surface is weathered to a depth of c. 2-3 mm.

3) The laminae are concentrations of small sand grains, iron oxide minerals and mica flakes.

4) Speckles are orange-brown, probably an altered iron-rich mineral.

5) Detrital grains are commonly well rounded, but enclosed by thick overgrowths of silica cement.

6) Rounded zircon grains are present in accessory proportion.

7) Most of the pores are partially infilled with clay minerals.

8) The carbonate mineral is iron-rich (ferroan dolomite, ankerite or siderite).




Figure A6_2. Two images of sample ED11048-1 as it appears in thin section. White grains are mainly quartz. Black areas are mainly iron oxide minerals. Greyish, mottled patches are carbonate mineral. Mottled bluish patches are clay mineral. Pore spaces appear clear blue. The field of view is 3.3 mm wide.


BGS sample number: ED11048-2 Sample dimensions: 90 x 65 x 25 mm PRIMARY_KE: 963306 Building address: Burgh Buildings Building stone: Buff sandstone 1


Hand specimen observations Stone type 1 (general classification): sandstone Stone colour 2 – fresh stone: very light buff Stone colour 2 – weathered stone: orangeish buff Stone colour 2 – exterior surface: green Stone cohesion 3 – fresh stone: moderately cohesive Stone cohesion 3 – weathered stone: moderately cohesive Primary sedimentary structure 4: uniform Distinctive features 5: faintly speckled Reaction to 10% HCl 6: strong Water absorption (permeability) 7: very high

Thin section observations

A thin section was not prepared.


Comments 1) The sample consists of a chip from rock-faced walling on the side elevation, at ground level.

2) The exterior surface is weathered to a depth of c.3 mm and is strong orangeish buff.

3) The faint speckles are of weak orange-brown colour due to iron oxide remobilization.

4) Strong reaction to 10% HCl suggests that calcite is present as a carbonate mineral cement.


There are no thin section images of this sample.


BGS sample number: ED11049-1 Sample dimensions: 80 x 55 x 30 mm PRIMARY_KE: 961318 Building address: The Steeple Building stone: Buff sandstone 1


Hand specimen observations Stone type 1 (general classification): sandstone Stone colour 2 – fresh stone: light buff to buff Stone colour 2 – weathered stone: light buff to buff Stone colour 2 – exterior surface: very light buff Stone cohesion 3 – fresh stone: strongly cohesive Stone cohesion 3 – weathered stone: very friable Primary sedimentary structure 4: parallel lamination Distinctive features 5: speckled Reaction to 10% HCl 6: moderate Water absorption (permeability) 7: moderate to high


Thin section observations

Stone constituents 8: Granular (detrital) constituents Intergranular constituents Quartz 62% Silica (overgrowth) 3% Feldspar 2% Feldspar (overgrowth) 0% Rock fragments 0% Carbonate 3% Mica 1% Iron/manganese oxide 6% Opaque material 0% Clay 10% Other 0% Hydrocarbon 0% Intragranular pores 1% Intergranular pores 12% Stone type 1 (detailed classification): subfeldspathic-arenite Grain-size 9: fine-sand-grade to medium-sand-grade Grain sorting 10: moderately well sorted Grain roundness 11: sub-angular to well-rounded Cement distribution 12: silica cement discontinuous; carbonate cement isolated Supergene changes 13: none


Comments 1) The sample consists of a small chip from the internal walling of The Steeple, at third floor level.

2) Faint laminae are formed by accumulations of iron oxide minerals and mica flakes.

3) Orange-brown speckles up to 1.5 mm across are composed mainly of iron oxide.

4) The carbonate mineral is iron-bearing (ferroan dolomite, ankerite or siderite)

5) A substantial proportion of the space between detrital grains is infilled by clay.

6) The stone shows parallel lamination, with hints of possible cross-lamination or ‘wispy bedding’.




Figure A6_3. Two images of sample ED11049-1, as it appears in thin section. White grains are mainly quartz. Black areas are mainly iron oxide minerals. Pore spaces appear blue. The field of view is 3.3 mm wide.


BGS sample number: ED11049-2 Sample dimensions: 190 x 35 x 25 mm PRIMARY_KE: 961318 Building address: The Steeple Building stone: Buff sandstone 1


Hand specimen observations Stone type 1 (general classification): sandstone Stone colour 2 – fresh stone: not applicable Stone colour 2 – weathered stone: light buff to buff Stone colour 2 – exterior surface: very light buff Stone cohesion 3 – fresh stone: not applicable Stone cohesion 3 – weathered stone: very friable Primary sedimentary structure 4: parallel lamination Distinctive features 5: speckled Reaction to 10% HCl 6: no Water absorption (permeability) 7: very high

Thin section observations

A thin section was not prepared.


Comments 1) The sample consists of a small chip from the internal walling of The Steeple, at third floor level.

2) The laminae consist of concentrations of iron oxide minerals and mica flakes.

3) The high permeability and friable character reflect the weathered condition of the stone. A former mineral cement composed of carbonate minerals may have dissolved due to weathering. 4) The exterior surface has a lime mortar wash and is therefore paler than the weathered stone.

5) Orange-brown speckles up to 1.5 mm across are probably weathered spots of iron oxide.



There are no thin section images of this sample.


BGS sample number: ED11049-3 Sample dimensions: 90 x 50 x 20 mm PRIMARY_KE: 961318 Building address: The Steeple Building stone: Buff sandstone 1


Hand specimen observations Stone type 1 (general classification): sandstone Stone colour 2 – fresh stone: very light buff Stone colour 2 – weathered stone: not applicable Stone colour 2 – exterior surface: very light greyish buff Stone cohesion 3 – fresh stone: moderately cohesive Stone cohesion 3 – weathered stone: not applicable Primary sedimentary structure 4: parallel lamination Distinctive features 5: faintly speckled Reaction to 10% HCl 6: strong Water absorption (permeability) 7: very high

Thin section observations

A thin section was not prepared.


Comments 1) The sample consists of a small chip from the internal walling of The Steeple, at third floor level.

2) The laminae consist of concentrations of iron oxide minerals and mica flakes.

3) Strong reaction to 10% HCl indicates the sandstone has a mineral cement of calcite.



There are no thin section images of this sample.


BGS sample number: ED11050 Sample dimensions: 90 x 30 x 20 mm PRIMARY_KE: 963257 Building address: 16 Melville Street Building stone: Buff sandstone 1


Hand specimen observations Stone type 1 (general classification): sandstone Stone colour 2 – fresh stone: buff Stone colour 2 – weathered stone: not applicable Stone colour 2 – exterior surface: grey Stone cohesion 3 – fresh stone: strongly cohesive Stone cohesion 3 – weathered stone: not applicable Primary sedimentary structure 4: uniform (some orientated grains) Distinctive features 5: carbonaceous matter Reaction to 10% HCl 6: none Water absorption (permeability) 7: high

Thin section observations

A thin section was not prepared.


Comments 1) The sample consists of a small chip from a mullion at first floor level.

2) The exterior surface is weathered to a depth of less of 1 mm, and is grey. It is not clear if the sample includes ‘fresh’ stone or has been collected from within a weathered outer layer on the masonry block. 3) Small fragments of carbonaceous matter are c.3 mm long.



There are no thin section images of this sample.


BGS sample number: ED11052 Sample dimensions: 120 x 90 x 50 mm PRIMARY_KE: not applicable Address: Viewfield pit, Bantaskine quarry Building stone: Buff sandstone 1


Hand specimen observations Stone type 1 (general classification): sandstone Stone colour 2 – fresh stone: very light greyish buff Stone colour 2 – weathered stone: light greyish buff Stone colour 2 – exterior surface: light greenish grey Stone cohesion 3 – fresh stone: strongly cohesive Stone cohesion 3 – weathered stone: moderately cohesive Primary sedimentary structure 4: parallel lamination Distinctive features 5: none Reaction to 10% HCl 6: strong Water absorption (permeability) 7: moderate


Thin section observations

Stone constituents 8: Granular (detrital) constituents Intergranular constituents Quartz 55% Silica (overgrowth) 2% Feldspar 1% Feldspar (overgrowth) 0% Rock fragments 0% Carbonate 10% Mica 2% Iron/manganese oxide 5% Opaque material <1% Clay 7% Other 1% Hydrocarbon 0% Intragranular pores 1% Intergranular pores 16% Stone type 1 (detailed classification): subfeldspathic-arenite Grain-size 9: fine-sand-grade Grain sorting 10: moderately sorted Grain roundness 11: sub-angular to well rounded Cement distribution 12: silica cement discontinuous; carbonate cement discontinuous Supergene changes 13: weak dissolution of feldspar; moderate alteration of biotite

Comments 1) The sample is from a quarry face in Viewfield Pit (Bantaskine quarry), from a well cemented tabular bed of sandstone that is interbedded with layers of shale and mudstone. 2) Thin brown laminae consist of concentrations of iron oxide and mica.

3) Rounded zircons (often in clusters) and biotite appear as accessory minerals.

4) Pore spaces are commonly not well connected; water absorption is therefore only moderate despite a relatively high proportion of pore space. 5) The stone is dominantly fine-sand-grade but thin layers are of very-fine-sand or silt grade.

6) Chlorite has replaced some of the detrital biotite.

7) Strong reaction to 10% HCl suggests calcite is present, but ferroan carbonate mineral is also present.

8) The fabric consists of parallel lamination with ‘wispy’ lamination in foreset packets. 9) Several percent of detrital feldspar and rock fragments have dissolved and are now clay minerals.




Figure A6_4. Two images of sample ED11052, as it appears in thin section. White grains are mainly quartz. Black areas are mainly iron oxide minerals. Brownish, mottled patches are carbonate mineral. Mottled bluish patches are clay mineral. Pore spaces appear clear blue. The field of view is 3.3 mm wide.


BGS sample number: ED11053-1 Sample dimensions: 125 x 80 x 40 mm PRIMARY_KE: not applicable Building address: demolished wall by Tattie Kirk Building stone: Buff sandstone 1


Hand specimen observations Stone type 1 (general classification): sandstone Stone colour 2 – fresh stone: buff Stone colour 2 – weathered stone: not applicable Stone colour 2 – exterior surface: light green Stone cohesion 3 – fresh stone: strongly cohesive Stone cohesion 3 – weathered stone: not applicable Primary sedimentary structure 4: parallel lamination Distinctive features 5: colour banding due to alteration; speckled Reaction to 10% HCl 6: strong Water absorption (permeability) 7: moderate to high

Thin section observations

Stone constituents 8: Granular (detrital) constituents Intergranular constituents Quartz 54% Silica (overgrowth) 3% Feldspar 7% Feldspar (overgrowth) 0% Rock fragments 2% Carbonate 3% Mica 2% Iron/manganese oxide 6% Opaque material 0% Clay 10% Other <<1% Hydrocarbon 0% Intragranular pores 3% Intergranular pores 10% Stone type 1 (detailed classification): subfeldspathic-arenite Grain-size 9: fine-sand-grade to medium-sand-grade Grain sorting 10: moderately sorted Grain roundness 11: sub-angular to well rounded Cement distribution 12: silica cement discontinuous; carbonate cement isolated Supergene changes 13: strong dissolution of feldspar


Comments 1) The parallel laminae consist of concentrations of iron oxide minerals and mica flakes.

2) Colour banding is due to Liesegang bands.

3) Ochre speckles up to 1 mm across are iron oxide mineral.

4) Clay occupies intergranular spaces and probably formed through alteration of dissolved feldspar and rock fragments. 5) Strong reaction to 10% HCl suggests the carbonate mineral is calcite.




Figure A6_5. Two images of sample ED11053-1, as it appears in thin section. White grains are mainly quartz. Light grey grains are mostly feldspar. Black areas are mainly iron oxide minerals. Brownish mottled patches are carbonate mineral. Mottled bluish patches are clay mineral. Pore spaces appear clear blue. The field of view is 3.3 mm wide.


BGS sample number: ED11053-2 Sample dimensions: 160 x 90 x 80 mm PRIMARY_KE: not applicable Building address: demolished wall by Tattie Kirk Building stone: Buff sandstone 1


Hand specimen observations Stone type 1 (general classification): sandstone Stone colour 2 – fresh stone: light greyish buff Stone colour 2 – weathered stone: not applicable Stone colour 2 – exterior surface: light green Stone cohesion 3 – fresh stone: strongly cohesive Stone cohesion 3 – weathered stone: not applicable Primary sedimentary structure 4: parallel lamination Distinctive features 5: none Reaction to 10% HCl 6: strong Water absorption (permeability) 7: high

Thin section observations

Stone constituents 8: Granular (detrital) constituents Intergranular constituents Quartz 46% Silica (overgrowth) 3% Feldspar 4% Feldspar (overgrowth) 0% Rock fragments 2% Carbonate 1% Mica 2% Iron/manganese oxide 3% Opaque material 0% Clay 15% Other <1% Hydrocarbon 0% Intragranular pores 4% Intergranular pores 20%

Stone type 1 (detailed classification): feldspathic-arenite Grain-size 9: fine-sand-grade to medium-sand-grade Grain sorting 10: moderately well sorted Grain roundness 11: sub-angular to well rounded Cement distribution 12: silica cement discontinuous Supergene changes 13: strong dissolution of feldspar


Comments 1) Parallel light brown laminae consist of concentrations of iron oxide minerals and mica flakes.

2) Tourmaline appears as an accessory mineral.

3) Most detrital grains are medium-sand-grade.

4) Carbonate mineral forms only a very small proportion of the thin section, so the strong reaction to 10% HCl may be due to contamination by lime mortar. 5) Clay minerals occupying pore spaces are a result of dissolution of feldspar and rock fragments.




Figure A6_6. Two images of sample ED11053-2, as it appears in thin section. White grains are mainly quartz. Black areas are mainly iron oxide minerals. Mottled bluish areas are clay mineral. Pore spaces are clear blue. The field of view is 3.3 mm wide.


BGS sample number: ED11053-5 Sample dimensions: 115 x 80 x 50 mm PRIMARY_KE: not applicable Building address: demolished wall by Tattie Kirk Building stone: Buff sandstone 1


Hand specimen observations Stone type 1 (general classification): sandstone Stone colour 2 – fresh stone: very light grey Stone colour 2 – weathered stone: not applicable Stone colour 2 – exterior surface: light green Stone cohesion 3 – fresh stone: strongly cohesive Stone cohesion 3 – weathered stone: not applicable Primary sedimentary structure 4: parallel lamination Distinctive features 5: none Reaction to 10% HCl 6: strong Water absorption (permeability) 7: high

Thin section observations

Stone constituents 8: Granular (detrital) constituents Intergranular constituents Quartz 40% Silica (overgrowth) 4% Feldspar 3% Feldspar (overgrowth) <1% Rock fragments 1% Carbonate 9% Mica 2% Iron/manganese oxide 3% Opaque material <1% Clay 12% Other <<1% Hydrocarbon 0% Intragranular pores 5% Intergranular pores 20% Stone type 1 (detailed classification): subfeldspathic-arenite Grain-size 9: fine-sand-grade Grain sorting 10: well sorted Grain roundness 11: sub-rounded to rounded Cement distribution 12: silica cement discontinuous; carbonate cement discontinuous Supergene changes 13: moderate dissolution of feldspar

Comments 1) Thin, wispy and parallel laminae consist of concentrations of iron oxide minerals and mica flakes. 2) Carbonate is probably calcite and dolomite. Some crystals have well formed faces (idiomorphic). 3) Platy crystals of mica are commonly long and kinked/crushed by compaction. 4) Very small rounded zircons appear as an accessory mineral. 5) The primary sedimentary structure is mainly parallel lamination but there is some ‘wispy’ lamination. 5) Clay minerals occupying intergranular pore spaces are due to dissolution of feldspar and rock fragments.




Figure A6_7. Two images of sample ED11053-5, as it appears in thin section. White grains are mainly quartz. Black areas are mainly iron oxide minerals. Brownish mottled patches are carbonate mineral. Mottled bluish areas are clay mineral. Pore spaces are clear blue. The field of view is 3.3 mm wide.


BGS sample number: ED11054 Sample dimensions: 210 x 80 x 75 mm PRIMARY_KE: 961318 Building address: The Steeple Building stone: Modern buff sandstone 4


Hand specimen observations Stone type 1 (general classification): sandstone Stone colour 2 – fresh stone: dull greyish buff Stone colour 2 – weathered stone: not applicable Stone colour 2 – exterior surface: greenish grey-buff Stone cohesion 3 – fresh stone: strongly cohesive Stone cohesion 3 – weathered stone: not applicable Primary sedimentary structure 4: uniform (some orientated grains) Distinctive features 5: none Reaction to 10% HCl 6: none Water absorption (permeability) 7: moderate to low


Thin section observations

Stone constituents 8: Granular (detrital) constituents Intergranular constituents Quartz 67% Silica (overgrowth) 3% Feldspar 3% Feldspar (overgrowth) 0% Rock fragments 10% Carbonate 0% Mica 1% Iron/manganese oxide 3% Opaque material <1% Clay 4% Other <<1% Hydrocarbon 0% Intragranular pores 2% Intergranular pores 7% Stone type 1 (detailed classification): sublithic-arenite Grain-size 9: fine-sand-grade to medium-sand-grade Grain sorting 10: well sorted Grain roundness 11: angular to sub-angular Cement distribution 12: silica cement discontinuous Supergene changes 13: moderate dissolution of feldspar; strongly remobilized iron


Comments 1) The sample is a fragment of the exterior dressed stone from ground level of The Steeple. The exterior surface is covered in a transparent coating, possibly to prevent water penetration. 2) Rounded zircons appear as an accessory mineral.

3) Mica flakes are both biotite and muscovite.

4) Porosity is relatively low (~9%) and pore spaces are poorly connected.




Figure A6_8. Two images of sample ED11054, as it appears in thin section. White grains are mainly quartz and off-white grains are mainly rock fragments. Black areas are mainly iron oxide minerals. Mottled bluish areas are clay mineral. Pore spaces are clear blue. The field of view is 3.3 mm wide.



BGS sample number: ED11060-1 Sample dimensions: 90 x 35 x 10 mm PRIMARY_KE: 963266 Building address: 25-29 Newmarket Street Building stone: Buff sandstone 4


Hand specimen observations Stone type 1 (general classification): sandstone Stone colour 2 – fresh stone: buff Stone colour 2 – weathered stone: not applicable Stone colour 2 – exterior surface: green Stone cohesion 3 – fresh stone: strongly cohesive Stone cohesion 3 – weathered stone: not applicable Primary sedimentary structure 4: uniform Distinctive features 5: none Reaction to 10% HCl 6: strong Water absorption (permeability) 7: moderate to high

Thin section observations

Stone constituents 8: Granular (detrital) constituents Intergranular constituents Quartz 66% Silica (overgrowth) 2% Feldspar 3% Feldspar (overgrowth) 0% Rock fragments 1% Carbonate 5% Mica 1% Iron/manganese oxide 7% Opaque material 0% Clay 5% Other <<1% Hydrocarbon 0% Intragranular pores 0% Intergranular pores 10% Stone type 1 (detailed classification): subfeldspathic-arenite Grain-size 9: fine-sand-grade to coarse-sand-grade Grain sorting 10: poorly sorted Grain roundness 11: sub-angular to well rounded Cement distribution 12: silica cement continuous Supergene changes 13: none


Comments 1) The sample consists of a small chip from the Vicar Street elevation at ground level. 2) The green colour of the exterior surface is due to biogenic growth. 3) Rounded zircons and tourmaline appear as accessory minerals. 4) Strong reaction to 10% HCl solution suggests the carbonate mineral is mainly calcite, but concentrations of secondary iron oxide minerals indicate a ferroan carbonate mineral was formerly present. 5) Clay minerals in the intergranular pore spaces are the result of dissolution of feldspar grains and rock fragments.




Figure A6_9. Two images of sample ED11060-1, as it appears in thin section. White grains are mainly quartz. Black areas are mainly iron oxide minerals. Grey mottled patches are carbonate mineral. Mottled bluish areas are clay mineral. Pore spaces are clear blue. The field of view is 3.3 mm wide.


BGS sample number: ED11060-2 Sample dimensions: 130 x 70 x 30 mm PRIMARY_KE: 963266 Building address: 25-29 Newmarket Street Building stone: Buff sandstone 4


Hand specimen observations Stone type 1 (general classification): sandstone Stone colour 2 – fresh stone: buff Stone colour 2 – weathered stone: not applicable Stone colour 2 – exterior surface: green and grey Stone cohesion 3 – fresh stone: moderately cohesive Stone cohesion 3 – weathered stone: not applicable Primary sedimentary structure 4: uniform Distinctive features 5: carbonaceous matter Reaction to 10% HCl 6: weak Water absorption (permeability) 7: high

Thin section observations

Stone constituents 8: Granular (detrital) constituents Intergranular constituents Quartz 62% Silica (overgrowth) 2% Feldspar 4% Feldspar (overgrowth) 0% Rock fragments 2% Carbonate 1% Mica 1% Iron/manganese oxide 6% Opaque material 0% Clay 7% Other <<1% Hydrocarbon 0% Intragranular pores 0% Intergranular pores 15%

Stone type 1 (detailed classification): subfeldspathic-arenite Grain-size 9: fine-sand-grade to coarse-sand-grade Grain sorting 10: poorly sorted Grain roundness 11: sub-angular to well rounded Cement distribution 12: silica cement continuous Supergene changes 13: none

Comments 1) The sample consists of a stone fragment from the west façade, adjacent to St Andrew’s West Church, at ground level. 2) Green and grey colours on the exterior surface are due to biogenic growth and soot.

3) Rounded zircons appear as an accessory mineral.

4) Clay minerals in the intergranular pore spaces are the result of dissolution of feldspar grains and rock fragments.




Figure A6_10. Two images of sample ED11060-2, as it appears in thin section. White grains are mainly quartz. Black areas are mainly iron oxide minerals. Mottled bluish areas are clay mineral. Pore spaces are clear blue. The field of view is 3.3 mm wide.


BGS sample number: ED11061 Sample dimensions: 90 x 30 x 30 mm PRIMARY_KE: 963242 Building address: 42 Newmarket Street Building stone: Buff sandstone 1


Hand specimen observations Stone type 1 (general classification): sandstone Stone colour 2 – fresh stone: very light greyish buff Stone colour 2 – weathered stone: greyish buff Stone colour 2 – exterior surface: greyish buff Stone cohesion 3 – fresh stone: moderately cohesive Stone cohesion 3 – weathered stone: moderately cohesive Primary sedimentary structure 4: uniform (some orientated grains) Distinctive features 5: carbonaceous matter; speckled Reaction to 10% HCl 6: moderate Water absorption (permeability) 7: high

Thin section observations

Stone constituents 8: Granular (detrital) constituents Intergranular constituents Quartz 59% Silica (overgrowth) 5% Feldspar 2% Feldspar (overgrowth) <1% Rock fragments 1% Carbonate 4% Mica 1% Iron/manganese oxide 2% Opaque material 0% Clay 10% Other <<1% Hydrocarbon 0% Intragranular pores 1% Intergranular pores 15% Stone type 1 (detailed classification): subfeldspathic-arenite Grain-size 9: fine-sand-grade to medium-sand-grade Grain sorting 10: moderately well sorted Grain roundness 11: sub-angular to sub-rounded Cement distribution 12: silica cement continuous; carbonate cement isolated Supergene changes 13: moderate dissolution of feldspar

Comments 1) The sample consists of a chip from a window jamb at first floor level.

2) The exterior surface is weathered to a depth of less than 1 mm, and is greyish buff.

3) A strongly speckled character is given by dark reddish brown spots of iron oxide.

4) Flakes of muscovite mica are relatively common and aligned, marking the bedding orientation.

5) The carbonate mineral is iron-rich (ferroan dolomite, ankerite or siderite).

6) There are occasional fragments of carbonaceous matter.

7) Clay minerals in the intergranular pore spaces are in large part the result of dissolution of feldspar grains and rock fragments.




Figure A6_11. Two images of sample ED11061, as it appears in thin section. White grains are mainly quartz. Black areas are mainly iron oxide minerals, which can form laminae (as in the lower image). Light grey, mottled patches are carbonate mineral. Mottled bluish areas are clay mineral. Pore spaces are clear blue. The field of view is 3.3 mm wide.


BGS sample number: ED11062 Sample dimensions: 45x25x10 mm PRIMARY_KE: 961108 Building address: 6-8 Cow Wynd Building stone: Buff sandstone 1


Hand specimen observations Stone type 1 (general classification): sandstone Stone colour 2 – fresh stone: light buff Stone colour 2 – weathered stone: not applicable Stone colour 2 – exterior surface: grey Stone cohesion 3 – fresh stone: moderately cohesive Stone cohesion 3 – weathered stone: not applicable Primary sedimentary structure 4: faintly laminated Distinctive features 5: none Reaction to 10% HCl 6: mild Water absorption (permeability) 7: high

Thin section observations

Stone constituents 8: Granular (detrital) constituents Intergranular constituents Quartz 62% Silica (overgrowth) 4% Feldspar 4% Feldspar (overgrowth) 0% Rock fragments 2% Carbonate 1% Mica 1% Iron/manganese oxide 2% Opaque material <1% Clay 8% Other <1% Hydrocarbon 0% Intragranular pores 1% Intergranular pores 15%

Stone type 1 (detailed classification): subfeldspathic-arenite Grain-size 9: fine-sand-grade to medium-sand-grade Grain sorting 10: moderately sorted Grain roundness 11: sub-angular to rounded Cement distribution 12: silica cement continuous Supergene changes 13: moderate dissolution of feldspar


Comments 1) The sample is a small chip from a quoin at the top of the first floor level.

2) The faint laminae consist of concentrations of iron oxide minerals and mica flakes.

3) Rounded grains of tourmaline and zircon appear as accessory minerals.

4) Most of the clay mineral content is probably due to alteration of feldspar grains and rock fragments.





Figure A6_12. Two images of sample ED11062, as it appears in thin section. White grains are mainly quartz. Black areas are mainly iron oxide minerals, which can form laminae (as in the lower image). Mottled bluish areas are clay mineral. Pore spaces are clear blue. The field of view is 3.3 mm wide.

Supporting notes for the petrographic descriptions

Each numbered note below relates to one of the superscript numbers in the preceding Petrographic Description forms. 1 Stone type: a low-precision (general classification) or high precision (detailed classification) name for the stone type. The determination of stone type follows the classification and nomenclature of the BGS Rock Classification Scheme. 2 Stone colour: the ‘visual’ determination of stone colour is based on a simple assessment with the unaided eye in natural light. Wherever possible, the determination of stone colour is made on a broken (not sawn), dry surface. 3 Stone cohesion: a simple, non-quantitative assessment of the degree to which the stone is cohesive. This property is recorded in terms of four conditions, each representing one segment of a continuum: strongly cohesive, moderately cohesive, moderately friable, and very friable. The grains in a strongly cohesive stone cannot be disaggregated by hand, whereas the grains in a very friable stone can be readily disaggregated by hand. 4 Primary sedimentary structure: a record of whether the distribution of granular (detrital) constituents in the sample is essentially isotropic (uniform) or anisotropic (non-uniform). The type of anisotropic fabric is recorded. 5 Distinctive features: a record of visible features that are distinctive and might be diagnostic; see Table 3 for a list of distinctive features for sandstone. 6 Reaction to 10% HCl: the visual reaction to a drop of dilute hydrochloric ac id placed on the surface of the stone. Used in sandstone to test whether a carbonate mineral cement is present; a strong fizzing reaction indicates that calcite is present, a weakly fizzing reaction indicates that dolomite may be present. 7 Water absorption (permeability): a simple, non-quantitative assessment of stone permeability, presented as one of five conditions (very low, low, moderate, high, very high) expressed relative to a nominal ‘average’ permeability in building stone sandstones. The assessment is based on the speed of water absorption using a water bead test. 8 Stone constituents: a record of the identity and relative proportions of all granular (detrital) and intergranular (authigenic materials and pore space) constituents currently in the stone. The proportions are estimates, expressed in %, which are based on a visual assessment of the whole thin section area. 9 Grain-size: the terms are those used for grain-size divisions in the BGS Rock Classification Scheme. 10 Grain sorting: a simple, non-quantitative assessment of the degree to which detrital constituents display similarity in terms of physical characteristics (in particular the size and shape of grains). 11 Grain shape: a simple, non-quantitative assessment of the degree to which detrital constituents are abraded. 12 Cement distribution: a record of the type and extent of mineral cement that acts to bind detrital grains, as observed in thin section. Isolated means the cement occurs in discrete locations (e.g. as overgrowths on individual detrital grains). Discontinuous means the cement is formed in patches, each of which typically encloses several to many detrital grains. Continuous means the cement is more-or-less connected across the thin section. 13 Supergene changes: a record of the evidence observed in thin section for mineral alteration that occurs in the stone when it is near the ground surface. Such alteration processes typically begin before stone is quarried, but some may continue, or be initiated, after stone is extracted from the ground.