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 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 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 , just scratched by steel
2 sets of cleavages intersecting at 60°/120°
Greenish black in colour
1cm

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

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

10. Andalusite/Chiastolite (silicate)
Hardness , 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. Hardness 3, just scratched by a copper coin
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 in colour
1cm

15. Halite or Rock Salt (halide)
Hardness , 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 , 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) Perfect cubic cleavage, 3 planes intersect at 90°
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. Just scratched by steel
Identify this mineral 1
90°
1cm
Just scratched by steel

23. Greenish black streak, barely scratched by steel
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 Scratched by steel but not by a copper coin
Cubic crystals with edges truncated at 45°
2cm
Scratched by steel but not by a copper coin

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

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

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

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

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

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

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

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

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

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

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

37. Scratched by a fingernail, fibrous/flaky, feels greasy
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. Very dense, scratched by a copper coin, grey streak
Name this mineral 18
1cm
Very dense, scratched by a copper coin, grey streak

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

41. Scratched easily by a fingernail, one plane of cleavage
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