Here's how to identify a mineral. Luster is the way a mineral reflects light and the first key step in mineral identification. Look for luster on a fresh surface. The three major types of luster are metallic, glassy (vitreous), and dull. Next, try to determine the hardness of your mineral. Use the 10-point Mohs hardness scale. The important hardnesses are between 2 and 7. For this, you'll need your fingernail (hardness about 2), a coin (hardness 3), a knife or nail (hardness 6.5), and a few key minerals. Properties Color Luster Special Properties White Dull/glassy Bubbles with acid Pink or white Dull/pearly Black/gray Mineral Hardness (Scratch Test) 3 Calcite scratched by nail 6 Feldspar scratches glass 2 Mica scratched by fingernail 1 Talc easily scratched by fingernail 2 Gypsum scratched by fingernail 7 Quartz scratches glass Fluorite 4 Shiny Splits into thin sheets White Dull White/gray Dull Various colors Glassy Most common mineral Various colors Glassy Can be striped; multicolored Problem You have been given a gray mineral that can be scratched with a fingernail. Based on the identification criteria, what two minerals can you narrow your sample to? A:Talc & Mica
B: gypsum & Talc
C:Mica and gypsum
D: Calcite &mica