Diamond Is The Hardest Mineral; No Other Mineral Can Scratch A Diamond. Quartz Is A 7. ... Mohs Hardness Scale.

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Table of contents

• Introduction
• MINERALS
• + What is Matter?
  • Atoms and Elements
  • Molecules and Compounds
• + What are Minerals?
  • Natural Processes
  • Inorganic Substances
  • Definite Composition
  • Solid Crystals
  • Physical Properties
• + Groups of Minerals
  • Silicate Minerals
  • Native Elements
  • Carbonates
  • Halides
  • Oxides
  • Sulfates
  • Sulfides
• + Lesson Summary
• IDENTIFICATION OF MINERALS
• + How are Minerals Identified?
  • Color, Streak, and Luster
  • - Color
  • - Streak
  • - Luster
  • Density and Hardness
  • - Density
  • - Hardness
  • Cleavage and Fracture
  • - Cleavage
  • - Fracture
  • Other Identifying Characteristics
• + Lesson Summary

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+ How are Minerals Identified?

- Hardness

Hardness is a mineral’s ability to resist being scratched. Minerals that are not easily scratched are hard. You test the hardness of a mineral by scratching its surface with a mineral of a known hardness. Mineralogists use the Mohs Hardness Scale, shown in Table below, as a reference for mineral hardness. The scale lists common minerals in order of their relative hardness. You can use the minerals in the scale to test the hardness of an unknown mineral.

Mohs Hardness Scale

As you can see, diamond is a 10 on the Mohs Hardness Scale. Diamond is the hardest mineral; no other mineral can scratch a diamond. Quartz is a 7. It can be scratched by topaz, corundum, and diamond. Quartz will scratch minerals that have a lower number on the scale. Fluorite is one. Suppose you had a piece of pure gold. You find that calcite scratches the gold. Gypsum does not. Gypsum has a hardness of 2 and calcite is a 3. That means the hardness of gold is between gypsum and calcite. So the hardness of gold is about 2.5 on the scale. A hardness of 2.5 means that gold is a relatively soft mineral. It is only about as hard as your fingernail.

Mohs Scale

Hardness	Mineral
1	Talc
2	Gypsum
3	Calcite
4	Fluorite
5	Apatite
6	Orthoclase feldspar
7	Quartz
8	Topaz
9	Corundum
10	Diamond