1. 8th Grade Integrated Science
Minerals and Rocks
8th Grade Integrated Science

2. Mineral Qualities What is a mineral?
To be a mineral a substance must have ALL of the following qualities
occur naturally - formed by nature, not by man
form from an inorganic process- from things that were never living
solid- tightly packed particles
crystalline structure-the atoms line up in a repeating pattern, flat sides called faces meet at sharp edges and corners.
definite chemical compostion- only certain elements in definite proportions.

3. Mineral Facts Almost all minerals are compounds
SOME elements are found in their pure form, not part of compounds
Copper (Cu), Gold (Au), Silver (Ag)
Almost all solid, pure elements are metals

4. Mineral Identification
Minerals can be identified from one another using specific properties.
The internal atomic structure of the mineral determines its properties
Color- the minerals color
Not dependable to identifying most minerals b/c most minerals have many colors ex. Hematite is black, grey, silver, brown, red
Very few common minerals have one color ex, sulfur (yellow)
Many minerals are the same color ex. Magnetite, hematite, mica (black)
Streak – the color of the minerals powder when rubbed on a streak plate
VERY RELIABLE
Streak for a mineral is ALWAYS the same color (no matter the color of the mineral

5. Mineral Identification
Moh's Hardness Scale
Hardness
Mineral
Description 1
Talc
Fingernail scratches it easily. 2
Gypsum
Fingernail scratches it. 3
Calcite
Copper penny scratches it. 4
Fluorite
Steel knife scratches it easily. 5
Apatite
Steel knife scratches it. 6
Feldspar
Steel knife does not scratch it easily, but scratches glass. 7
Quartz
Hardest common mineral. It scratches steel and glass easily. 8
Topaz
Harder than any common mineral. 9
Corundum
It scratches Topaz. 10
Diamond
It is the hardest of all minerals.
Luster – the way the mineral shi-nes/reflects light
Metallic- shines like a metal
Non metallic – does not look like a metal
Pearly - ex, mica
Glassy – ex. Quartz, halite
Dull/earthy – ex. Hematite (red)
Waxy – ex. talc
Brilliant – ex. Diamond
Hardness – how easily a mineral is scratched
fingernail (hardness = 2.5)
copper penny (hardness = 3)
Iron nail (hardness = 4)
glass plate or steel knife (hardness = 5.5)
steel file (hardness = 6.5)
Ceramic tile (hardness = 7)

6. Mineral Identification
Breakage
Cleavage – mineral breaks along smooth, flat surfaces (due to internal structure of atoms)
Fracture – mineral breaks unevenly, irregularly, or in jagged surfaces
Density - (specific gravity how tightly packed the particles of a mineral are for a given volume compared to water
Heavy – ex. galena, gold
Medium – ex. quartz, feldspar
Light – ex. mica, sulfur
Other properties
Chemical – will react with HCl (hydrochloric acid), bubbles
or “fizzes”
Magnetic
Double refraction – bends light to create double image
Fluorescence – glows in UV light
Taste
Smell

7. Mineral Lab Samples

8. Use of Minerals
Ore - a naturally occurring solid material from which a metal or valuable mineral can be profitably extracted
Metals – good conductors of heat and electricity
Alloy – mixture of two or more metals and non metals (bronze, brass, steel)
Gems – used in jewelry, hardness greater than 7, rare, valuable

9. How minerals form Organic processes
Minerals form three ways
Organic processes
ALL minerals form by inorganic processes, BUT some form from organic processes as well
Ex. ocean animals (clams and corals) produce shells and skeletons made out of calcite
From materials dissolved in solutions
Water evaporates leaving minerals behind
Hot water heated by magma cools and
minerals dissolved crystalize
Vein- narrow channel of mineral that is different that the surrounding rock
Cooling magma and lava
Slow cooling = large crystals
Fast cooling = small crystals