What is a Mineral?

Properties: Solid Naturally Occurring Inorganic Fixed composition Cannot be a liquid or a gas Naturally Occurring Found in nature, not man-made Inorganic Is not alive and never was, non-living Fixed composition Has a chemical formula, most are formed from compounds of two or more elements, some minerals consist of one element ex. Au Crystal Form A definite structure in which atoms are arranged

Definition: A mineral is a naturally formed, inorganic solid that has a definite crystalline structure.

The next few slides show an assortment of items. Questions to ask yourself when determining if an item is a mineral or not: Is it non-living material? Is it a solid? Is it formed in nature? Does it have a crystalline structure? The next few slides show an assortment of items. As a group, categorize the items as either: Minerals or Non-Minerals.

Wood

Gold

Fossil

Topaz

Bones

Granite

Quartz

Pearls

Talc

Icebergs

Diamond

Coal

Rock Salt

And the answers are… Minerals Non-Minerals Gold Topaz Quartz Talc Iceberg* Diamonds Non-Minerals Wood - once living Fossils – once living Bone - living material Granite - intrusive igneous rock Pearls – made by oysters Coal - Sedimentary rock Rock Salt – Sedimentary rock According to IMA – ice is listed as a mineral. Why?

Two Groups of Minerals Nonsilicates Silicates Do not contain combinations of Si and O May contain C, O, F, S Classes of Nonsilicates Native Elements: Au, Cu, Ag Oxides : Al or Fe combine with O Carbonates: C + O Sulfates: S + O Halides: F, Cl, I, or Br combine with Na, K, or Ca Sulfides: Pb, Fe, Ni, combine with S Silicates Contains Silicon (Si) and Oxygen (O) 90% of Earth’s crust Combine with elements such as Al, Fe, Mg, and K

Identifying Minerals Color – the same mineral can come in a variety of colors, not reliable

Luster – the way in which a mineral reflects light Metallic - opaque and reflective, like metal Submetallic - to nearly opaque and reflect well Nonmetallic - not looking like a metal at all Vitreous - glassy Silky - fibrous Resinous – yellow, dark orange, brown Waxy Pearly – like inside a mollusk Earthy – dull, looks like dirt or clay

Streak – the color of the mineral in a powdered form Cleavage – when minerals break along a smooth, flat surface Fracture – when minerals break unevenly along a curved or irregular surface

Hardness – a minerals resistance to being scratched Moh’s Scale of Hardness 1 - 10

Density – how much matter is in a given amount of space Special Properties Fluorescence – glow under ultraviolet light Chemical Reaction – fizzes with acid test Optical Properties – double image formed Magnetism – magnetic, attract iron Taste – salty Radioactivity – radium or uranium contained