Milky quartz with iron staining

Mostly white to translucent gray, with rusty orange-brown staining and a vitreous to dull luster; quartz has Mohs hardness 7, a trigonal crystal structure, and no cleavage, breaking with irregular or conchoidal fractures. The specimen’s rough, irregular form is consistent with vein quartz, though identification from the image alone is uncertain.

Quartz commonly forms when silica-rich fluids fill fractures and crystallize in veins; it occurs in rocks of many ages and geological settings.

Commonly collected; clear or attractive material may be cut or polished. Quartz is also used in glassmaking, electronics, and industrial abrasives.

Iron oxides such as limonite can produce the orange-brown surface discoloration.

Look for glassy luster, hardness sufficient to scratch glass, and lack of cleavage; quartz veins are widespread worldwide. Avoid relying on color alone, since several minerals can resemble it.