Chapter 3- Minerals (Geology)

Mineral Definition (5 Rules)

1. Natural. 2. Inorganic. 3. Solid. 4. Crystalline Structure. 5. Definite Chem. Comp.

glass

a solid in which atoms are not organized in an orderly pattern

crystal

a single continuous piece of mineral bounded by flat surfaces that formed naturally as the crystal grew

crystal faces

flat surfaces of a crystal, formed during the crystals growth

polymorphs

two minerals that have the same chemical composition but different crystalline structures

4 ways minerals form

1. solidification from magma

2. precipitation

3. solid-state diffusion

4. biomineralization

solidification from magma

occurs when molten rock cools, allowing atoms to bond and arrange into an ordered crystalline structure, forming minerals.

Streak

the color of a mineral's powder

Cleavage, 1 Plane

Breaks into thin Sheets (eg. Mica)

Cleavage, 3 planes at 90 degrees

Breaks into Cubes (e.g., Halite).

Conchoidal Fracture

Smooth, curved break (no cleavage, e.g., Quartz).

Most common mineral group

silicates (eg Quartz and Feldspar)

precipitation from a water solution

when dissolved ions bond together to form crystals that settle out of the water

solid-state diffusion

slow movement of atoms through a solid, allowing minerals to form or change without melting.

biomineralization

The process by which living organisms form minerals inside their bodies to build structures like shells, bones, teeth, or skeletons by controlling how ions crystallize.

ways minerals are destroyed

1. melting

2. dissolution

3. chemical reactions

4. microbial metabolism

dissolution

when you immerse a mineral in a solvent, such as water. Atoms or ions then separate from the crystal face and are surrounded by solvent molecules.

chemical reactions

when a mineral comes in contact with a reactive mineral.

microbial metabolism

when microbes “eat” certain minerals and use the energy stored in chemical bonds for metabolism.

melting

heating a mineral to a temperature in which thermal vibration of the atoms or ions break the chemical bonds holding the mineral together.

mineral identification

color, streak, luster, hardness, specific gravity (density), crystal habit (crystal faces), special proproerties, cleavages

mineral classes

silicates, sulfides, oxides, halides, carbonates, native metals, suflates