Minerals Earth Science. What is a Mineral? In Geology… A mineral is a naturally occurring, inorganic solid that has a crystal structure and a definite.

Minerals Earth Science What is a Mineral? In Geology A mineral is a naturally occurring, inorganic solid that has a crystal structure and a definite chemical composition. Some examples Naturally Occurring Seen in nature. Not man made. Inorganic Cannot form from material that was once living Cannot form from material that was once living Organic = life! Organic = life! Crystal Structure Mineral particles line up in a pattern that repeats itself over and over again. Definite Chemical Composition Definite = always the same Minerals always contain the same elements in the same ratios. SiO 2 KAlSi 3 O 8 Solid Definite volume and shape How do Minerals form? Crystallization of melted material (aka magma/lava) Minerals form as magma cools Crystallization of materials dissolved in water When hot water cools or evaporates, minerals crystallize Where do we find Minerals? Most of Earths crust is made up of common minerals (like quartz) Less common minerals are not evenly distributed around the planet Many valuable minerals are found in or near areas of volcanic activity or mountain building. Where can you find diamonds? Where can you find oil? Why do we care? All rocks are made of at least one mineral! How can we differentiate minerals and rocks?? Many minerals are important to our daily lives Gemstone Metals (Silver, copper) In foods, medicines, fertilizers, building materials Is it formed in nature? Is it non-living material? Does it have a chemical composition? Does it have a crystalline structure? Is it solid? Wood Gold Fossil Topaz Bones Granite Quartz Pearls Talc Icebergs Diamond Coal Glass Minerals 2 - Gold 4 - Topaz 6 - Quartz 9 - Talc 10 - Iceberg* 11 - Diamonds Non-Minerals 1 - Wood - once living 3 - Fossils once living 5 - Bone - living material 7 - Granite - intrusive igneous rock 8 - Pearls made by oysters 12 - Coal - Sedimentary rock 13 - Glass-Human made * According to IMA ice is listed as a mineralIMA MINERALS 1. Naturally occurring 2. Inorganic 3. Solid 4. Crystal structure (due to internal arrangement of atoms) 5. Definite chemical composition General Facts about Minerals Over 5,000 have been identified A few are native elements -- made of only one element, such as sulfur, gold. copper, and graphite (carbon) Most are compounds, especially the silicate group (Si, O). Earths crust is 90% silicate rocks! Other important groups are oxides, carbonates, and sulfides. Less than a dozen are common in most rocks Quartz Feldspar (group) Muscovite (white mica) Biotite (black mica) Calcite Pyroxene Olivine Amphibole (group ) Magnetite, limonite, and other iron oxides Pyrite We will identify many of these in our LAB activity : ) Silicates Silicon and oxygen are two of the most abundant elements on earth Silicates are the most plentiful minerals on earth They are built around covalent bonds (Chemistry!) of silicon and oxygen Symbols Silicon = Si Oxygen = O Silicates can build in a variety of ways OSi O O O O O OO OO O O O O O O O In flat sheets like mica Or in crystals 0 Si Si Or in crystals like quartz Minerals are identified by their key characteristics Hardness Crystal structure Luster Color Streak Cleavage/fracture Density Special Properties reaction to acid fluorescence salty taste magnetism odor Mineral Hardness Ability to scratch another mineral Mohs Hardness Scale from 1 (talc) to 10 (diamond) Quartz (most common mineral) is 7 Color results from ability to absorb some wavelengths and reflect others some minerals have characteristics colors Streak Color of the powder when rubbed on a streak plate (unglazed porcelain) May be same as hand- specimen or different Some paint is based on powdered minerals (streaks). Luster Describes how light reflects off the surface Main categories are metallic and non- metallic Non-metallic includes dull, glassy, waxy, pearly Density (Specific Gravity) All minerals have density (mass / volume), but some are very dense Examples include galena, magnetite, and gold Specific Gravity is the density of the mineral compared with density of water Crystal Shape (Form) External structure due to internal arrangement of the atoms Six basic groups of shapes, with about three dozen variations Mineral cleavage/fracture A mineral that splits easily along flat surfaces when struck hard--this is called mineral cleavage Fracture- Describes how a mineral looks when it breaks apart in an irregular way. A few minerals have both cleavage and fracture Special Characteristics Many minerals have some special characteristic that helps us identify that mineral. Special Characteristics-- Fluorescence Some minerals will glow when placed under short-wave or long-wave ultraviolet rays Franklin and Ogdensburg NJ are famous for their fluorescent minerals Fluorescent Minerals Special Characteristic-- Salty Taste DO NOT TASTE the MINERALS! Halite -it will taste salty, just take my word for it. Special Characteristics-- Magnetism Many iron minerals will produce an invisible magnetic force field Lodestone was used by Vikings more than 1,000 years ago as compasses Special Properties- reacts to acid Calcite will bubble up when acid is poured on it. Common uses include: Aluminum--packaging, transport, building Beryllium--gemstones, fluorescent lights Copper--electric cables, wires, switches Feldspar--glass and ceramics Iron--buildings, automobiles, magnets Calcite--toothpaste, construction