Mineral ID: Cleavage/Fracture Streak

The name of a scientist that studies rocks and minerals is called a . . . 

• biologist
• geologist
• zoologist
• rockologist

Cleavage can be described as

• unpredictable and random breakage

• the predictable way minerals break along weak bonding planes

• the color of a mineral powder

This is galena. The cleavage is described as

• good, in 3 directions, cubic habit

• poor in, in 1 direction, basal habit

• no cleavage--only fracture

What is the dominant form of breakage seen in this magnetite?

• cleavage

• fracture

This mineral is gypsum. It has a hardness of 2. The cleavage would be described as

• good, in 1 direction, basal habit

• poor, in 2 directions, prismatic habit

• no cleavage--only fracture

• poor, in 3 directions, cubic habit

Pictured is a quartz crystal. This mineral has NO cleavage. Explain

• the flat sides you see are NOT broken--the crystal grew that way

• Quartz is not a mineral so therefore it can't have cleavage

Halite (table salt) has a cleavage this is described as

• poor, cuboidal

• basal

• good, in 3 directions, cubic habit

• none of these

Halite and calcite have perfect (good) cleavage in 3 directions, but calcite is different because it has

• rhombohedral crystal habit

• cleavage in 3 directions

Some minerals we will not be able to find a STREAK of because they are

• radioactive

• made of CO2

• harder than a streak plate

This is the most common mineral. It is a silicate (SiO2) so it does not react to acid. It is 7 hardness with NO cleavage--only fracture.

• halite

• quartz

• calcite

• gypsum