1. AS-A level Geology Mineral Guide
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2. Eduqas AS-A level Mineral Guide

3. 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

4. Orthoclase Feldspar (silicate)
Hardness 6, not scratched by steel
2 cleavages intersecting at 90° results in blocky shape
Commonly pink in colour
Crystals may show simple twinning
2cm

5. Plagioclase Feldspar (silicate)
Hardness 6, not 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 under a microscope
1cm

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

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

8. Hornblende (amphibole/silicate)
Hardness , just scratched by steel
2 sets of cleavages intersecting at 60°/120°
Black – dark green in colour
Vitreous lustre

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

10. Hardness 6.0-7.0, not scratched by a steel nail
Olivine (silicate)
Hardness , not scratched by a steel nail
Olive green in colour
No cleavage
Vitreous lustre
2cm

11. 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

12. 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,

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)
1cm
Hardness 4, scratched easily by a steel nail 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

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

16. Gypsum (sulphate) Hardness 1.5 -2.0, easily scratched by a fingernail
Perfect basal (parallel) cleavage
Often fibrous in appearance (satin spar)
2cm

17. Barytes/Barite (sulphate)
Hardness , just 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
Metallic lustre
Bronze-yellow colour
Tarnishes to peacock colours

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

20. Galena (sulphide) 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, not scratched by steel
Cherry red streak
Metallic lustre
Kidney shaped masses with a fibrous internal structure
1cm