Diagnostic properties of some rock-forming minerals

Question 1

What is the colour, streak and lustre of Quartz

Answer 1

colour- varies; often white or grey
Streak- none
lustre-vitreous/ shiny

Question 2

What is the shape and cleavage/ fracture of quartz?

Answer 2

shape- irregular

cleavage/ fracture- none/ irregular

Question 3

What is the hardness and density of quartz?

Answer 3

hardness- 7

density- 2.7gcm^3

Question 4

What is the colour, streak and lustre of Feldspar?

Answer 4

colour- pink, white or grey
streak- white
lustre- vitreous/ dull

Question 5

What is the shape and cleavage/ fracture of feldspar?

Answer 5

shape- approximately rectangular

cleavage/ fracture- Two directions

Question 6

What is the hardness and density of feldspar?

Answer 6

Hardness- 6

Density- 2.6gcm^3

Question 7

What is the colour, streak and lustre of Mica?

Answer 7

colour-white (muscovite), dark (biotite)
streak- white/grey
lustre-vitreous

Question 8

What is the shape and cleavage/ fracture of mica?

Answer 8

shape- sheets/ flakes

cleavage/ fracture- good in one direction

Question 9

what is the hardness and density of mica?

Answer 9

hardness- 2.5-3

density- 2.8gcm^3

Question 10

What is the colour, streak and lustre of Augite?

Answer 10

colour- dark green to black
streak- white/ grey
lustre- vitreous

Question 11

What is the shape and cleavage/ fracture augite?

Answer 11

shape- square or eight sided in cross section

cleavage/ fracture- two directions almost at right angles (93*)

Question 12

What is the hardness and density of augite?

Answer 12

Hardness- 5.5-6.5

density- 3.2-3.6 gcm^3

Question 13

What is the colour, streak and lustre of hornblende?

Answer 13

colour- green to black
streak- white/ grey
lustre- vitreous/ shiny

Question 14

What is the shape and cleavage/ fracture of hornblende?

Answer 14

shape- diamond shaped in cross section

cleavage/ fracture- two directions at about 60 degrees (56*)

Question 15

What is the hardness and density of hornblende?

Answer 15

hardness- 5-6

density- 3.0- 3.5 gcm^3

Question 16

What is the colour, streak and lustre of olivine?

Answer 16

colour- yellow green
streak- white/ grey
lustre- vitreous

Question 17

What is the shape and cleavage/ fracture of olivine?

Answer 17

shape- rounded

cleavage/ fracture- poor/ conchoidal

Question 18

What is the hardness and density of olivine?

Answer 18

hardness- 6.5-7

density- 3.2-4.4 gcm^3

Question 19

What is the colour, streak and lustre of calcite?

Answer 19

colour- white grey or transparent
streak- white
lustre- vitreous

Question 20

What is the shape and cleavage/ fracture of calcite?

Answer 20

shape- irregular/ rhombic

cleavage/ fracture- three directions rhombohedral

Question 21

What is the hardness and density of calcite?

Answer 21

hardness-3

density-2.7 gcm^3

Question 22

What is the colour, streak and lustre of Garnet?

Answer 22

colour- deep red to brown
streak- white
lustre- vitreous

Question 23

What is the shape and cleavage/ fracture of garnet?

Answer 23

Shape- rounded/ six sided in cross section

cleavage/ fracture- none/ poor conchoidal

Question 24

What is the hardness and density of garnet?

Answer 24

hardness- 6-7.5

density- 4 gcm^3

Question 25

What is the colour, streak and lustre of kyanite?

Answer 25

colour- blue, white or grey streak- white lustre- vitreous

Question 26

What is shape and cleavage/ fracture or kyanite?

Answer 26

shape- flat/ blades | cleavage/ fracture- two directions

Question 27

What is the hardness and density of Kyanite?

Answer 27

hardness- 5.5-7 | density- 3.5-3.7 gcm^3