Mineral Characterisitics Number 1 Number 2 Number 3

Mineral Characterisitics

Number 1 Number 2 Number 3 Number 4 Number 5 Number 6 Number 7 Number 8 Describe in Own Words Color Streak Luster Texture

Color • Most notable characteristic • Caused by presence of trace elements • Quartz= orange citrine (iron hydrates) purple amethyst (ferric iron), red jasper (iron oxide): • Least reliable characteristic

Streak • Color of the powder of a mineral • Rub mineral across unglazed porcelain plate • Sometimes, does not match color of mineral • Pyrite (fool’s gold)= greenishblack • Gold= yellow • Only performed if softer than porcelain • Can not be used to identify all minerals

Luster • Way a mineral reflects light from its surface • Metallic vs. Nonmetallic • Dull, pearly, waxy, silky, greasy • Caused by chemical compositions

Cleavage and Fracture • How a mineral breaks • Splits easily and evenly=cleavage • Break with rough/jagged edges= fracture

Texture • How mineral feels to the touch • Smooth, rough, ragged, greasy, soapy, glassy

Hardness • Most useful tool • How easily it can be scratched • Moh scale= 1 -10 • Determined by arrangement of mineral’s atoms

Rating Type mineral What it can be scratched by… 1 Talc Baby powder 2 Gypsum fingernail 3 Calcite bronze coin 4 Fluorite iron nail 5 Apatite glass 6 Feldspar penknife blade 7 Quartz steel knife 8 Topaz sandpaper 9 Corundum 10 Diamond

Density and Specific Gravity • Density reflects atomic weight and structure. Useful, but sometimes differences are too small to be noticed by lifting • Specific gravity: used by geologist. Ratio of 0 weight to equal volume of water at 4 C

Special Properties • Refraction: light bent in 2 directions when passed through mineral (zircon) • Fizzing with contact of hydrochloric acid (calcite) • Magnetic (iron ore) • Distinctive rotten egg odor when streaked (sphalerite)

• 1. Explain why color is not a good test for distinguishing between pyrite and gold • 2. What test is most reliable for distinguishing between pyrite and gold. • 3. What is a mineral’s texture? List several words used as a description • 4. The mineral fluorite can be found in a variety of colors, yet its streak is always white. Why can fluorite be found in different colors? Why is the streak always the same?