This document provides information on 20 different minerals. For each mineral, it gives the mineral name, key physical properties such as hardness, crystal structure, cleavage, color, and identifying characteristics. Pictures or diagrams are also provided to illustrate some mineral characteristics. The minerals discussed include common rock-forming silicates as well as oxides, sulfides, carbonates, halides, and sulfates. Key identification tests involving hardness tests, streak tests, cleavage, crystal habit, and other properties are summarized for each mineral.

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)
1cm 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

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
2cm
Whitish, straw or
silvery in colour

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

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
2cm
No cleavage
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
1cm inclusions in the centre,
like lead in a pencil

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
1cm from amphiboles,
pyroxenes and micas
Chlorite, Val Di Vizze, Italy

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

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 2.0-2.5,
2cm
scratched by a
fingernail
Perfect cubic
cleavage, 3 planes
intersecting at 90°
Tastes salty when
put on the tongue
Halite, Neuhof, Germany

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

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
1cm peacock colours

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 90°
traces
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
1. Augite 11. Plagioclase
2. Iron Pyrite 12. Biotite
3. Olivine 13. Haematite
4. Fluorite 14. Muscovite
5. Garnet 15. Chiastolite
6. Orthoclase 16. Chlorite
7. Barytes 17. Chalcopyrite
8. Halite 18. Galena
9. Hornblende 19. Calcite
10.Quartz 20. Gypsum