Crocidolite, (blue asbestos,) alters to quartz, but while retaining its fibrous structure. This material is frequently stained by iron, giving […]

Thomsonite cabochons take a high polish but are somewhat brittle. These are especially lovely when a pinkish gray eyelike pattern

For a long time, rare thaumasite crystals — pale, fragile, and with little to no fire — were interesting primarily

Tephroite is generally reddish brown and barely translucent. However, it takes a good polish and is massive enough to make

Tektite is a natural glass formed from the ejected debris of meteorite impacts. Though most pieces are very small, some

Tanzanite has had a rapid rise to prominence among jewelers and gem enthusiasts. Although naturally reddish brown, this transparent zoisite

Tantalite is too dark to be of use as a faceted gem but is sometimes cut as a collector curiosity,

An overview on Talc Jewelry and Gemstones. Covers details and essential information on the physical properties and characteristics of Talc

Taaffeite reacts to most gemological tests like mauve-colored spinel, but can be distinguished on the basis of its birefringence. Additional

Sunstones contain hematite or goethite inclusions, which reflect light in parallel orientation and create a sparkling sheen in gold to