Rock Identifier
Yellow Topaz (Imperial or Precious Topaz) (Al2SiO4(F,OH)2 (Aluminum Silicate Fluoride Hydroxide)) — mineral
mineral

Yellow Topaz (Imperial or Precious Topaz)

Al2SiO4(F,OH)2 (Aluminum Silicate Fluoride Hydroxide)

Hardness: 8 on Mohs scale; Color: Pale yellow to golden sherry; Luster: Vitreous (glassy); Crystal Structure: Orthorhombic; Cleavage: Perfect basal; Specific Gravity: 3.4 to 3.6.

Hardness
8 on Mohs scale
Color
Pale yellow to golden sherry
Luster
Vitreous (glassy)
Identified More mineral

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Physical properties

Hardness: 8 on Mohs scale; Color: Pale yellow to golden sherry; Luster: Vitreous (glassy); Crystal Structure: Orthorhombic; Cleavage: Perfect basal; Specific Gravity: 3.4 to 3.6.

Formation & geological history

Formed through fluorine-bearing vapors given off during the late stages of crystallization in igneous rocks like pegmatites and rhyolites; also found in alluvial deposits. Age varies by location but occurs in ancient pegmatite veins.

Uses & applications

Primarily used as a gemstone in high-end jewelry (rings, pendants) and widely sought after by mineral collectors. It is the birthstone for November.

Geological facts

Topaz is one of the hardest naturally occurring minerals. Historical 'Imperial Topaz' was named to honor the Russian Tsars of the 19th century and specifically refers to the orange-pink to golden-yellow varieties.

Field identification & locations

Identify in the field by its high harness (scratches glass/quartz) and perfect basal cleavage (ability to split along the base). Commonly found in Ouro Preto, Brazil; Russia (Urals); and Pakistan. Collectors should look for its distinctive flattened crystal faces.