Mineral Cleavage and Hardness

The video tutorial by Professor Dave explains how to identify minerals based on their physical characteristics such as luster, color, cleavage, and fracture patterns. It discusses the importance of cleavage in mineral identification, using examples like graphite and quartz. The tutorial also covers the Mohs Hardness Scale, which ranks minerals by their ability to scratch each other, and provides practical tips for using common objects to estimate mineral hardness. The video concludes by relating atomic structures to macroscopic properties and introduces the next topic of crystal chemistry.

What is the term used to describe a mineral that breaks along a planar surface in one or more directions?

• Luster

• Hardness

• Cleavage

• Fracture

Which mineral is known for its conchoidal fracture pattern?

• Graphite

• Halite

• Calcite

• Quartz

How can you differentiate between halite and calcite based on their cleavage?

• Halite has no cleavage, calcite has one

• Halite has three directions at 90 degrees, calcite at 60 and 120 degrees

• Both have the same cleavage angles

• Calcite has no cleavage, halite has one

What is the hardness of a typical human fingernail on the Mohs scale?

• 4.5

• 3.5

• 2.5

• 5.5

If a mineral can be scratched by a steel file but not by a penny, what is its likely hardness range on the Mohs scale?

• 3.5 to 6.5

• 1 to 2

• 7 to 8

• 2.5 to 3