Rock and Mineral Exam Study Guide

Rock and Mineral Exam Study Guide - Minerals are classified...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Minerals are classified by: Luster, hardness, streak, cleavage, color, other How to determine minerals: 1. Check luster- metallic, nonmetallic? 2. Check hardness- <5.5? Check streak o Colored streak? o White to faintly colored streak? Check cleavage No cleavage One or more cleavages o >5.5: White/whitish streak/ Check cleavage No cleavage One or more cleavages Color Determined by slight impurities or defects within crystal structure Generally diagnostic for minerals with metallic luster May vary with NML Luster Appearance of mineral when light is reflected on surface Can be metallic or nonmetallic Vitreous- like that of glass Dull- earthy appearance Pearly- like a pearl Greasy- as though covered by coat of oil Waxy- like paraffin Resinous luster- like resin or tree sap Nonmetallic luster Can be any color Thin pieces or edges are generally transparent to light Hardness Resistance to abrasion or scratching Mohs Hardness Scale Streak Color of mineral when finely powdered May or may not be same color as the mineral Talc, Gypsum, Calcite, Fluorite, Apatite, Orthoclase, Quartz, Topaz, Corundum, Diamond (The greedy commoner fought aggressively over Queen Tasha’s CD) Cleavage Breaks along parallel, flat surfaces Basal cleavage- one cleavage Three cleavages- cubic cleavage, or rhombohedral if not at 90º 4 CP- Octahedron 6 CP- Dodecahedron Conchoidal fracture Small, smooth, curved surfaces Fracture
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Breaks along uneven surfaces Graphite 1 CP (not always visible) Gray to black H=1 Greasy feel M Luster Usually found in meta rocks Bauxite: Pea shaped structures May be white, gray, red Usually soft, dull, earthy Forms by extensive weathering in tropical to subtropical cimates Galena 3 (sometimes perfect cubic) CP Silvery gray H=2.5 Pyrite Brass-yellow H=6-6.5 Massive or as crystals (cube, pyritohedron) Greenish black to black S Common in igneous, sedimentary, and metamorphic rocks Concentrated in veins or irregular masses Magnetite Dark gray to black H=6 May have dull luster if surface not fresh Attracted to magnet Black S Metallic luster on fresh breaks
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/07/2008 for the course GEOLOGY 111 taught by Professor Sheldon during the Fall '07 term at SUNY Geneseo.

Page1 / 7

Rock and Mineral Exam Study Guide - Minerals are classified...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online