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WJEC AS Mineral Guide

WJEC AS Mineral Guide. I.G.Kenyon. Quartz ( silicate ). Hardness 7, not scratched by steel No cleavage but shows conchoidal fracture Hexagonal crystals terminated by pyramids. 5mm. 1cm. Quartz (variety citrine). Rose quartz showing conchoidal fracture. Orthoclase Feldspar (silicate).

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WJEC AS Mineral Guide

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  1. WJEC AS Mineral Guide I.G.Kenyon

  2. Quartz (silicate) Hardness 7, not scratched by steel No cleavage but shows conchoidal fracture Hexagonal crystals terminated by pyramids 5mm 1cm Quartz (variety citrine) Rose quartz showing conchoidal fracture

  3. Orthoclase Feldspar (silicate) Hardness 6, barely scratched by steel 2 cleavages intersecting at 90° results in blocky shape Commonly flesh coloured Crystals show simple twinning 2cm

  4. Plagioclase Feldspar (silicate) Hardness 6, barely scratched by steel 2 sets of cleavages intersecting at 90° resulting in blocky form Commonly creamy white or grey in colour Crystals show multiple or repeated twins 1cm

  5. Biotite Mica (silicate) Hardness 2.5-3.0 scratched by a copper coin Shows perfect basal (parallel) cleavage Has a distinct pearly lustre Brown or black in colour 2cm

  6. Muscovite Mica (silicate) Hardness 2.5-3.0 scratched by a copper coin Shows perfect basal (parallel) cleavage Has a distinct pearly lustre Whitish, straw or silvery in colour 2cm

  7. Hornblende (amphibole/silicate) Hardness 5.0-6.0, just scratched by steel 2 sets of cleavages intersecting at 60°/120° Greenish black in colour 1cm

  8. Augite (pyroxene/silicate) Hardness 5.0-6.0, just scratched by steel 2 sets of cleavages intersecting at 90° Greenish black in colour

  9. Olivine (silicate) Hardness 6.0-7.0, not scratched by steel Olive green in colour No cleavage 2cm Olivine, Canary Islands

  10. Andalusite/Chiastolite (silicate) Hardness 6.5-7.5, not scratched by steel Occurs as needle-like crystals but square in cross-section Crystals have dark inclusions in the centre, like lead in a pencil 1cm

  11. Garnet (silicate) Hardness 6.5-7.5, not scratched by steel Rhombdodecahedral crystal form, 12 faces each one a rhombus No cleavage Red/brown or green in colour 2cm Almandine Garnet, Peru

  12. Chlorite (silicate) Hardness 2.0, scratched by fingernail Perfect basal (parallel) cleavage Greenish colour Feels greasy when rubbed between the fingers Alteration product from amphiboles, pyroxenes and micas 1cm Chlorite, Val Di Vizze, Italy

  13. Calcite (carbonate) Hardness 3, just scratched by a copper coin Perfect rhombohedral cleavage, 3 planes intersect at 60°/120° to give cleavage rhombs Effervesces and gives off carbon dioxide when dilute hydrochloric acid is applied 1cm

  14. Fluorite (halide) Hardness 4, scratched easily by steel but not by a copper coin Perfect octahedral cleavage, cubic crystals have the corners missing at a 45° angle Fluoresces in ultra violet light Commonly purple, green or yellow incolour 1cm

  15. Halite or Rock Salt (halide) Hardness 2.0-2.5, scratched by a fingernail Perfect cubic cleavage, 3 planes intersecting at 90° Tastes salty when put on the tongue 2cm Halite, Neuhof, Germany

  16. Gypsum (sulphate) Hardness 1.5 -2.0, easily scratched by a fingernail Perfect basal (parallel) cleavage Often fibrous in appearance (satin spar) Arrow head/fish tail twinned crystals common 2cm

  17. Barytes/Barite (sulphate) Hardness 3.0-3.5, barely scratched by a copper coin Dense for a non-metallic mineral (4.5) Often shows perfect basal (parallel) cleavage, occasionally displays 2 cleavages Commonly shows bladed crystal 2cm

  18. Chalcopyrite (sulphide) Hardness 4, not scratched by a copper coin Black streak with gold strands within it Metallic lustre Greenish gold colour Tarnishes to peacock colours 1cm

  19. Iron Pyrite/Pyrite (sulphide) Greenish black streak Hardness 6.0, barely scratched with steel Metallic lustre Brassy gold colour Cubic crystals show striated faces Strikes fire (sparks) with steel 1cm

  20. Galena (sulphide) 1cm Perfect cubic cleavage, 3 planes intersect at 90° Hardness 2.5, easily scratched by a copper coin Lead grey streak Very dense (7.5)

  21. Haematite (oxide) Hardness 5.5-6.5, barely scratched by steel Cherry red streak Metallic lustre Often occurs as kidney shaped masses with a fibrous internal structure 1cm

  22. Identify this mineral 1 90° 1cm Just scratched by steel

  23. Identify this mineral 2 1cm Greenish black streak, barely scratched by steel

  24. Identify this mineral 3 2cm Not scratched by steel, no cleavage

  25. Identify this mineral 4 Cubic crystals with edges truncated at 45° 2cm Scratched by steel but not by a copper coin

  26. Identify this mineral 5 2cm Not scratched by steel, crystal has 12 faces

  27. Identify this mineral 6 2cm Cleavage traces 90° Barely scratched by steel, crystals often show simple twins

  28. Identify this mineral 7 2cm Feels dense, barely scratched by a copper coin

  29. Identify this mineral 8 Cleavage directions 1cm 1cm Just scratched by fingernail

  30. Identify this mineral 9 60° 120° Cleavage traces 2cm Just scratched by steel

  31. Identify this mineral 10 2cm Not scratched by steel

  32. Identify this mineral 11 Cleavage traces 90° 2cm Barely scratched by steel, crystals often show multiple twins

  33. Identify this mineral 12 Cleavage traces 2cm Scratched by a copper coin

  34. Identify this mineral 13 2cm Barely scratched by steel, cherry red streak

  35. Identify this mineral 14 1cm Can be just scratched by a fingernail

  36. Identify this mineral 15 5mm Not scratched by steel, needle-like crystals

  37. Identify this mineral 16 1cm Scratched by a fingernail, fibrous/flaky, feels greasy

  38. Name this mineral 17 2cm Scratched easily by steel but not by a copper coin, black streak with gold strands

  39. Name this mineral 18 1cm Very dense, scratched by a copper coin, grey streak

  40. Name this mineral 19 1cm Reacts with acid, barely scratched by a copper coin, 3 cleavages

  41. Name this mineral 20 Cleavage traces 1cm Scratched easily by a fingernail, one plane of cleavage

  42. Name this mineral - Answers • Augite • Iron Pyrite • Olivine • Fluorite • Garnet • Orthoclase • Barytes • Halite • Hornblende • Quartz 11. Plagioclase 12. Biotite 13. Haematite 14. Muscovite 15. Chiastolite 16. Chlorite 17. Chalcopyrite 18. Galena 19. Calcite 20. Gypsum

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