Minerals
Minerals make up rocks.
Rocks break down and create baby rocks and minerals
There are many kinds of minerals, some are elements and some are compounds.
Some elements occur in nature in a pure form. They are usually metals Some elements occur in nature in a pure form. They are usually metals. Examples of elements that are also minerals: Copper, Silver, Gold
Some minerals are Compounds: Compounds are two or more atoms that are chemically combined to form something new. Quartz crystal: Silicon Dioxide: SiO2 Pyrite: Fool’s Gold: FeS2: iron sulfide
1. Naturally Occurring formed by a process that occurred in the natural world. Quartz forms naturally as magma cools and hardens deep below the earth’s surface. NOT: plastic, brick, glass, steel 2. Inorganic Not made from materials that were once living. Coal is NOT a mineral because it comes from the remains of plants that lived millions of years ago.
3. Solid— definite volume and shape. Not a liquid or gas. 4 3.Solid— definite volume and shape. Not a liquid or gas. 4.Crystal structure— The repeating pattern of the mineral’s particles with flat sides called FACES that meet at sharp edges and corners. Example: Quartz vs. Coal
5. Definite chemical composition— always contain certain elements in specific proportions. Example: Quartz has 1 atom of silicon and 2 atoms of oxygen.
Why is coal not a mineral Why is coal not a mineral? Quartz Coal Naturally Occurring Yes Yes Inorganic Yes NO Solid Yes Yes Crystal Structure Yes NO Definite Chem. Comp. Yes NO
Why is coal not a mineral and diamonds are minerals Why is coal not a mineral and diamonds are minerals? Aren’t diamonds made out of coal? Diamonds are made of carbon ONLY. Not organic carbon. Crystalline structure. Coal is a hydrocarbon: comes from organic material. Diamonds are NOT actually formed from organic coal. That is a myth. Pseudoscience.
Identifying Minerals (9 Characteristics)
Scientists have identified 3,800 minerals Scientists have identified 3,800 minerals. It’s difficult sometimes to tell them apart, so we conduct tests to observe their properties or characteristics.
Crystal Shape The crystals of each mineral grow atom by atom to form the mineral’s crystal structure. Sometimes obvious, sometimes microscopic.
1. Crystal Shape
Fluorite: octahedral
2. Color
Color Malachite is always green, azurite is always blue.
3. Streak The color of its powder when rubbed on an unglazed porcelain tile. The color of a mineral may vary, but the color of its streak is always the same. Pyrite has a gold color but greenish/black streak. Real Gold has a golden yellow streak.
4. Hardness – Moh’s Scale
5. Cleave. break evenly into layers 5.Cleave *break evenly into layers *splits easily along a flat surface Mica and Feldspar
Mica
6. Fracture break unevenly into chunks EX: Obsidian has a shell-like fracture like chipped glass
7.Luster - shininess metallic non-metallic
Types of Luster: Metallic—galena, an ore of lead Nonmetallic-everything else Glassy—quartz Earthy—hematite Waxy—talc Silky—malachite
8. Light Characteristics: Transparent – can see through Translucent – lets light through Opaque – blocks light calcite Selenite
Selenite Fluorite
Other light characteristics Fluorescence: Glows under black light Phosphorescence: Glows after being exposed to light (after light is turned off) Agate, analcime, andersonite, anglesite, apatite, aphthitalite (greenish), apophyllite,aragonite, barite, cahnite , calcite, celestite, cerussite, colemanite, diopside, esperite,fluorite, foshagite , gypsum, hanksite, hemimorphite, idrialite (variety - curtisite, greenish), laumontite, melanophlogite, nahcolite, ... Pink calcite
9. Density The density of a mineral is always the same for that mineral. Density=mass volume
Mass—measurement from a balance Mass—measurement from a balance. Volume—how much water it displaces when placed into a graduated cylinder.
Special Properties Some minerals have very unique characteristics that help us identify them. Magnetite—magnetism (attracts iron) Aragonite and Calcite—reacts chemically to acid