Quartz is a very common rock-forming mineral.
Color: highly variable, from clear/colorless to purple (amethyst), pink (rose quartz), yellow (citrine), gray (smoky quartz), white (milky quartz), et cetera
Diaphaneity: transparent to translucent; may appear to be opaque in some hand specimens
Specific gravity: 2.65
Cleavage/fracture: fractures "conchoidally" along irregular-shaped surfaces
Other distinguishing properties:Quartz is harder than, and lacks the planar cleavage of, other minerals it might be mistaken for, including fluorite (which typically fluoresc es in UV light), calcite (which fizzes in dilute hydrochloric acid), halite (which tastes like salt), and gypsum (which is soft enough to be scratched by a fingernail).
Klein, C., and Hurlbut, C.S., Jr., 1999, Manual of Mineralogy (after James D. Dana) [21st edition, revised]: New York, John Wiley & Sons, 682 p.
Los Angeles County Museum of Natural History, The Photo Atlas of Minerals: nhm.org/pam/
Return to the Minerals page.