Monday, April 21, 2014 Minerals Intro Warm Up: 1) Update Planners! 2) Reminders: STAAR Math tomorrow STAAR Reading Wednesday Do you know your testing room? Apr 21 7:21 AM Minerals Naturally occurring and Solid Inorganic Definite chemical composition Crystal structure due to internal arrangement of atoms 1
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 2
Common uses include: Aluminum packaging, transport, building Feldspar glass and ceramics Fluorite toothpaste Graphite pencil lead Gypsum sheet rock, plaster of Paris, chalk Talc powder, make up Minerals are identified by their physical properties Physical Property: can be observed or measured without changing the identity of the matter hardness crystal shape (form) luster color streak cleavage/fracture density (specific gravity) special properties reaction to acid fluorescence salty taste magnetism 3
Mineral Hardness Is a mineral's resistance to scratching Ability to scratch another mineral Mohs Scale from 1 (talc) to 10 (diamond) Quartz is the 2nd most abundant mineral in the continental crust. *It is in all three rock types and is the most resistant mineral to weathering Crystal Shape Some minerals have special or repeating shapes External structure due to internal arrangement of the atoms Some minerals form special geometric shapes like cubes or rhombehedrons 4
Luster Describes how a mineral reflects light Main categories are metallic and non metallic Non metallic includes: dull, glassy, waxy, pearly Color results from ability to absorb some wavelengths and reflect others Depends on the chemicals present The easiest to observe, but the least helpful in identification because of the large variety of colors for many of the minerals 5
Streak is the color of a mineral when ground to a fine powder Color of the powder when rubbed on a streak plate (unglazed porcelain) May be different from the mineral color Mineral cleavage/fracture Some minerals split along flat surfaces when struck hard this is called mineral cleavage Other minerals break unevenly along rough or curved surfaces this is called fracture A few minerals have both cleavage and fracture 6
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 Special Characteristics the Acid Test Carbonates react with dilute HCl and other acids by fizzing or bubbling (releasing carbon dioxide gas) 7
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 http://www.sterlinghill.org/tour%20information.htm Special Characteristics Salty Taste DO NOT TASTE MOST MINERALS! Halite is the exception it will taste salty 8
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 Useful Web Sites www.mii.org www.mineral.galleries.com/minerals www.mineral.net www.usgs.gov 9
Mohs Hardness Scale 1 Talc 2 Gypsum 3 Calcite 4 Fluorite 5 Apatite 6 Feldspar 7 Quartz 8 Beyrl 9 Corundum 10