Minerals

WHAT THINGS AROUND YOU ARE MADE OF MINERALS??? LOOK AROUND THE ROOM WHAT THINGS AROUND YOU ARE MADE OF MINERALS??? EVERYTHING!!!

MINErals Everything in this classroom and school, and any other man-made structure was mined out of the Earth. Mining is the extraction of materials out of the Earth’s crust for human use So…what are minerals? Rocks? Trees? Diamonds? Oil? Water?

Nutritional Definition Minerals are the natural chemical elements that are required by living organisms to survive. As in “Vitamins and Minerals”.

Economic Definition Minerals are a concentration of naturally occurring solid, liquid, or gaseous material in or on the Earth’s crust in such form and amount that extraction is economically feasible. Basically, natural materials that can be mined and sold for a profit

Scientific Definition Minerals are….. Naturally occurring Inorganic Solids They have definite chemical (formula) compositions They have ordered atomic structures (bonding patterns)

Minerals on Earth Of the 5,000 known minerals there are only a dozen or so rock forming minerals that compose most of the Earth. These minerals share the most abundant elements in the crust.

4 Ways that minerals form Crystallization from magma 2. Precipitation from water 3. High pressure and temperature recrystallization 4. Hydrothermal solutions

How are minerals identified and classified? The 4th and 5th parts of the definition… Definite chemical compositions (formula) Ordered atomic structures (bonding patterns) - result in each mineral having a set of unique physical, observable characteristics

Physical Characteristics include... Color Streak Luster Hardness Fracture and cleavage Density *Note that size is not a physical characteristic*

Color Color of some minerals is a very useful characteristic to use in identifying them. Sometimes it is not This sulfur for example is almost always yellow. Quartz can be almost any color

STREAK Streak is the color of the mineral in its powdered form. The powder is left behind when the mineral is rubbed on a piece of unglazed porcelain, the streak plate

Luster Luster is the way in which a mineral reflects, refracts, or absorbs light….in other words the way that it shines.

Luster may be Metallic or non-metallic This is the metallic luster of the mineral Galena. Metallic means Silver or Gold. Black and shiny is not necessarily metallic

Non-metallic lusters may be earthy, pearly, glassy, dull, waxy, resinous, or silky.

Hardness Hardness is a mineral’s resistance to being scratched. NOT ITS RESISTANCE TO BREAKING!!! Tested with fingernail and glass scratch plate

A numerical scale (Moh’s) from 1-10 is used to measure the hardness of minerals. Talc is the softest mineral at #1 Diamond is hardest at #10

Procedure for Hardness Test 1.) Does the mineral scratch glass Yes  hardness is > 5.5 No – go to step 2 2.) Does my nail scratch the mineral Yes  hardness is < 2.5 No  hardness is between 2.5 and 5.5

Cleavage or Fracture is the way to describe how a mineral breaks. If the mineral breaks along smooth, flat, parallel surfaces, it is said to have cleavage. “predictable” If the mineral breaks along rough, irregular surfaces, it is said to have fracture. “random”

TYPES OF CLEAVAGE CUBIC OCTAHEDRAL BASAL RHOMBIC

Why do minerals break the way they do? Minerals that have cleavage do because they break along parallel planes of weakness This is due to the internal arrangement and unequal bonding of their atoms. Minerals that fracture have equal (or close to it) atomic bonding in all directions You can remember a meat cleaver and a bone fracture to keep these terms straight.

BASAL -BREAKS IN SHEETSweb

Density Density is the ratio of a mineral’s mass to its volume. Dense minerals, such as Galena, are said to be “heavy for their size”.

Remember!!! The physical properties of a mineral are determined by: 1. It’s chemical make-up 2. the arrangement of its atoms.

Common Mineral Groups... Silicates The 2 most abundant elements in the earth’s crust are oxygen and silicon. Si02 These combine to form an atomic structure called a silicate tetrahedron. Silicates typically form from magma and/or extreme pressure. Quartz

This is a silicate tetrahedron This is a silicate tetrahedron. It is the building block for the silicate minerals such as quartz and feldspar. Very common building block. SILICA OXYGEN

Carbonates A group of minerals in which carbon and oxygen combine to form a carbonate CO3 molecule. Typically form from precipitation The test for these is the bubble test. When exposed to hydrochloric acid they release CO2 and they bubble. Borax Calcite

Oxides are compounds made of oxygen and metal, can form in virtually any geologic setting

Sulfates Contain SO4 molecule Forms from evaporating water (precipitation) Gypsum var. Selenite

Sulfides combinations of one or more metals with sulfur Sulfides combinations of one or more metals with sulfur . Typically hydrothermal PbS FeS2

Halides Halite - NaCl Fluorite – Ca2F Contain a halogen ion from group 7a in periodic table Ex. F, Cl, Br, and I Salt water evaporites Halite - NaCl Fluorite – Ca2F

Native elements Contain one element only Ex. Gold, copper, silver, etc. Hydrothermal