San Diego Natural History Museum--Your Nature ConnectionSDNHM Field Guide
[Topaz. Collection of the San Diego Natural History Museum.]

Topaz

From the Greek, topazos, for any stone that has lost its name.

Description and Occurrence

Topaz crystals are usually shaped like prisms, with fine vertical ridges (striations) on the crystal faces. The crystals come in a variety of colors: clear, yellow, blue, green, violet, or reddish brown. The most highly prized color is a deep, golden-yellow variety, though blue and green stones are popular also.

Until the mid-nineteenth century, topaz was considered a rare and valuable gemstone. When rich fields of topaz were discovered in Brazil, the value of the mineral collapsed. Today, Brazil is still considered the world's best source of topaz. Topaz also occurs in Sri Lanka, Mexico, Japan, and Russia.

Fine samples have been found in Little Three Pegmatite, near Ramona in San Diego County

Field Notes: Topaz is very hard and translucent (light passes through it). It cleaves easily and perfectly on a plane parallel to its base.


Physical Properties

Color Streak Transparency Luster Hardness Cleavage Fracture Specific gravity Crystal form
colorless, yellow, brown, blue, green colorless transparent to translucent vitreous 8 perfect, one basal direction conchoidal, uneven 3.5 to 3.6 orthorhombic

Photo: Topaz. Collection of the San Diego Natural History Museum
Photo credit: Linda West

Field Guide: Minerals | Field Guide Feedback Form