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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). - PowerPoint PPT Presentation
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WJEC AS Mineral Guide
I.G.Kenyon
Quartz (silicate)
1cm
Quartz (variety citrine)
Hardness 7, not scratched by steel
No cleavage but shows conchoidal fracture
Hexagonal crystals terminated by pyramids
Rose quartz showing conchoidal fracture
5mm
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
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
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
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
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
Augite (pyroxene/silicate)
Hardness 5.0-6.0, just scratched by steel
2 sets of cleavages intersecting at 90°
Greenish black in colour
Olivine (silicate)
Hardness 6.0-7.0, not scratched
by steel
Olive green in colour
No cleavageOlivine, Canary Islands
2cm
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 pencil1cm
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
Almandine Garnet, Peru
2cm
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 micasChlorite, Val Di Vizze, Italy
1cm
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
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
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
Halite, Neuhof, Germany
2cm
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
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
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 colours1cm
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
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)
1cm
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
Identify this mineral 1
90°
Just scratched by steel
1cm
Identify this mineral 2
Greenish black streak, barely scratched by steel
1cm
Identify this mineral 3
Not scratched by steel, no cleavage
2cm
Identify this mineral 4
Scratched by steel but not by a copper coin
Cubic crystals with edges truncated at 45°
2cm
Identify this mineral 52cm
Not scratched by steel, crystal has 12 faces
Identify this mineral 62cm
Barely scratched by steel, crystals often show simple twins
Cleavage traces
90°
Identify this mineral 7
Feels dense, barely scratched by a copper coin
2cm
Identify this mineral 8
Just scratched by fingernail
1cm1cm
Cleavage directions
Identify this mineral 9
Cleavage traces
120°60°
Just scratched by steel
2cm
Identify this mineral 10
Not scratched by steel
2cm
Identify this mineral 11
2cm
90°
Cleavage traces
Barely scratched by steel, crystals often show multiple twins
Identify this mineral 12Cleavage
traces
2cm
Scratched by a copper coin
Identify this mineral 13
Barely scratched by steel, cherry red streak
2cm
Identify this mineral 14
Can be just scratched by a fingernail
1cm
Identify this mineral 15
Not scratched by steel, needle-like crystals
5mm
Identify this mineral 16
Scratched by a fingernail, fibrous/flaky, feels greasy
1cm
Name this mineral 17
Scratched easily by steel but not by a copper coin, black streak with gold strands
2cm
Name this mineral 181cm
Very dense, scratched by a copper coin, grey streak
Name this mineral 191cm
Reacts with acid, barely scratched by a copper coin, 3 cleavages
Name this mineral 20
1cm
Scratched easily by a fingernail, one plane of cleavage
Cleavage traces
Name this mineral - Answers
1. Augite
2. Iron Pyrite
3. Olivine
4. Fluorite
5. Garnet
6. Orthoclase
7. Barytes
8. Halite
9. Hornblende
10.Quartz
11. Plagioclase
12. Biotite
13. Haematite
14. Muscovite
15. Chiastolite
16. Chlorite
17. Chalcopyrite
18. Galena
19. Calcite
20. Gypsum