1. GCSE Geology
Mineral Guide
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2. Minerals on the GCSE Data Sheet
GCSE Mineral Guide
Minerals on the GCSE Data Sheet

3. Quartz (silicate) Hardness 7, not scratched by steel
Glassy lustre
Hardness 7, not scratched by steel
No cleavage but shows conchoidal fracture
Hexagonal crystals terminated by pyramids
5mm
Rose quartz showing conchoidal fracture

4. Feldspar (Orthoclase) (silicate)
Hardness 6, not scratched by steel
2 cleavages at 90°results in blocky shape
Light orange or pinkish in colour
Glassy lustre
2cm

5. Feldspar (Plagioclase) (silicate)
1cm
Hardness 6, not scratched by steel
2 cleavages at 90° results in blocky form
Creamy white or grey in colour
Glassy lustre

6. Mica (Biotite) (silicate)
Hardness 2.5 scratched easily by a copper coin
Shows one good cleavage
Has a distinct pearly lustre
Brown or black in colour
2cm

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

8. Augite (silicate) Hardness 5.5, not scratched by steel
2 cleavages intersecting at 90°
Black in colour
Glassy lustre

9. Olivine (silicate) Hardness 6.5, not scratched by steel No cleavage
Olive green colour
Scratches the streak plate
Glassy Lustre

10. Garnet (silicate) Hardness 7.0, not scratched by steel No cleavage
Red colour
Scratches the streak plate
Glassy Lustre
Found in schists and formed by the regional metamorphism of shale

11. Hardness 3, scratched by a copper coin
Calcite (carbonate)
Hardness 3, 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
Glassy lustre

12. Halite or Rock Salt (halide)
Hardness 2.5, scratched easily by a copper coin
Perfect cubic cleavage, 3 planes intersecting at 90°
Tastes salty when put on the tongue
Glassy lustre

13. Galena (sulphide) Perfect cubic cleavage, 3 planes intersect at 90°
Hardness 2.5, easily scratched by a copper coin
Lead grey streak
Very dense (7.4)
Metallic lustre

14. Haematite (oxide) Hardness 5.5, may just be scratched by steel
Red-brown streak
Metallic lustre
Often occurs as kidney shaped masses with a fibrous internal structure
Quite dense
1cm