non silicates - sulfides

Question 1

identify the following mineral:
habit:
- definite cubic/isometric habit 
colour:
- dark grey/brown
streak colour:
- brown/yellow
hardness:
- 3/4
cleavage:
- apparently max six
Lustre:
- vitreous

Answer 1

sphalerite

Question 2

identify the following mineral:
habit:
- cubic 
colour:
- distinct metallic silver colour 
streak colour:
- dark grey 
lustre:
- metallic 
clevage:
-cubic 
three directions
- perfect/good 
hardness:
- 3/4 (scratched by steel nail)

Answer 2

Galena

Question 3

what are the diagnostic properties of galena?

Answer 3

• has a distinct metallic silver colour
• metallic lustre
• has a dark grey streak colour
• three cleavage directions and cubic habit

Question 4

what are the diagnostic properties of sphalerite?

Answer 4

• brown/yellow streak
• definte cubic habits
• brownish/grey colour of the cubic habit

Question 5

identify the following mineral:
habit:
- cubic 
colour:
-brassy/gold yellow 
streak:
- dark grey
lustre:
- metallic 
hardness:
- 5/6
cleavage:
-none

Answer 5

pyrite

Question 6

what are the diagnostic properties of pyrite?

Answer 6

1. cubic habit
2. brassy/ dull gold colour
3. NO clevage

Question 7

what does the chalcocite sulfide sample look like?

Answer 7

Dark blue-grey to brown-black, slight metal smell, greasy to dull lustre, stains fingers slightly, one sample has heavy white to red marbling on top other has slight white marbling

Question 8

what does the sphalierite sulfide sample look like?

Answer 8

Mostly black with red-brown undertone, black streak, few visible crystals, larger samples about length of palm

Question 9

what does the cinnibar sulfide sample look like?

Answer 9

Crimson red with black veins, larger sample has rough surface but smaller samples have been polished

Question 10

What is The diagnostic properties of sphalerite?

Answer 10

Its yellow/pale brown streak and hardness of 3/4

Question 11

What does galena resemble and can thus help you identify it?

Answer 11

A sheet sillicate. It looks as if it’s in easily flaky sheets

Question 12

Identify the following sulfide:
Habit:
- equant/isometric 
Aggregation:
- the majority of lab specimens are massive 
Colour:
Green gold colour. Almost looks like a green rock coated in a sheen of gold 
Streak: 
- strong dark grey streak. Glides easy
Hardness:
- 5/6 (scratched by quartz glass)
Lustre:
- metallic/ greasy
Cleavage:
- one poorly formed direction visible

Answer 12

Chalcopyrite

Question 13

What are the diagnostic properties of chalcopyrite?

Answer 13

• it has a very obvious colour, of being green with a sheen of gold over it
• metallic lustre
• the streak is a strong dark grey, and glides easily

Question 14

Identify the following mineral: 
Habit:
- no habit as is a massive specimine 
Lustre:
- two samples show earthy or greasy/dull 
Colour:
- distinct red or yellow brown colour 
Hardness:
- 3/4 (scratched by steel nail)
Cleavage:
- one poor direction not visible in both samples

Answer 14

Cinnabar

Question 15

What are the diagnostic properties of cinnabar?

Answer 15

• the very distinct red colour (if you get this sample in the lab)
• the hardness 3/4
• the fact that the lab samples are all massive

Question 16

How would you identify chalcocite?

Answer 16

It’s black
Has a hardness of 3/4
Earthy/dull lustre
Leaves a dark streak colour

Question 17

When you did a practice exam you mistook chalcocite for copper. Why?

Answer 17

It smelt of copper, but remember that copper itself is a lot softer