Earth Science Chapter 3

How are some minerals formed?

All minerals are formed by natural processes (without human input).

What is the difference between cleavage and fracture?

Cleavage breaks along smooth, flat surfaces. Fracture breaks with uneven, rough surfaces.

What are the classification systems of crystals?

Crystal shapes depend on how its atoms are arranged. Crystal shapes are organized into groups known as crystal systems. these systems are: Cubic, Tetragonal, Hexagonal, Orthorhombic, Monoclinic, and Triclinic.

Cubic Crystals system

Fluorite is an example of a minderal that forms cubic crystals. Minerals in the cubic crystal system are equal in size along all three principal dimensions

What is hardness?

Hardiness is a measure of how easily a mineral can be scratched.

Which minerals are soft?

Talc, Gypsum, Calcite, Fluorite

What is a mineral?

A mineral is a naturally occuring inorganic solid, with a definite chemical composition and an orderly arrangement of atoms

What is an ore? When is it or is it not an ore?

A mineral or a rock is an ore if it contains a useful substance that can be mined at a profit.

Hexagonal Crystals system

In hexagonal crystals, horizontal distances between opposite crystals surfaces are equal. These crystal surfaces intersect to form 60* or 120* angles. The vertical lenght is longer or shorter than the horizontal lengths.

What is luster?

Luster is the way a mineral refelcts light.

Monoclinic Crystal system

Minerals in the monoclinic system, such as orthoclase, also exhibit unequal dimensions in their crystal structure. Only one right angle forms where crystal surfaces meet. The other angles are oblique, which means they don't form 90* angles where they intersect.

What is cleavage?

Minerals that break along smooth, flat surfaces have cleavage.

What is fracture?

Minerals that break with uneven, rough, or jagged surfaces have fracture.

Orthorhombic Crystals system

Minerals with orthorhombic structure, such as barite, have dimensions that are unequal in length, resulting in crystals with a brick-like shape.

What is the largest group of rock forming minerals?

Silicates. Silicates are minerals that are composed of silicon and oxygen.

What happens when magma cools and how crystals form?

The size of the crystals that form depends partly on how rapidly the magma cools. When magma cools slowly, the crystals that form are large.

Triclinic crystal system

The triclinic crystal system includes minerals exhibiting the least symmetry. Triclinic crystals, such as rhodonite, are unequal in all dimensions and all angles where crystal surfaces meet are oblique.

Why is titanium useful?

Titanium is a nontoxic metal, it is durable, and it is lightweight. It is strong.

Tetragonal Crystals system

Zircon crystals are tetragonal. Tetragonal crystals are much like cubic crystals, except one of the principal dimensions is longer or shorter than the other two dimensions.

What are characteristics of gems?

color, hardiness and translucency

How do we identify minerals?

color, hardness, luster, specific gravity, streak, cleavage and fracture, unique properties

crystals from solution

crystals can form from minerals dissolved in water

What is a crystal system?

the crystal system divides crystals based upon their shapes and sizes.