is a calcium aluminium variety of Grossular
Garnet with hydroxide (OH) partially replacing silica (SiO4). The identity
of the members of the hydro-garnet family (Grossular, Hydrogrossular,
Hibschite and Katoite) depend on the degree of substitution
of hydroxide for silica.
Hydrogrossular is typically
translucent to opaque, rarely transparent, and found in various
shades of green to bluish green, pink, white and gray. The green color is due
to the presence of chromium and/or possibly iron. Pink Hydrogrossular is colored
by the presence of manganese. Green Hydrogrossular may contain small dark gray to black inclusions. Opaque
to translucent Hydrogrossular may look similar to Jade
but has no relationship to Jade. Hydrogrossular has been
incorrectly referred to as Transvaal Jade or African Jade.
Hydrogrossular is found in massive crystal habit, sometimes intergrown in with Idocrase.
Hydrogrossular is occassionally available as cabochons
but rarely available as clean, transparent, faceted
gemstones. These rare, transparent gems are a beautiful
yellowish green with slight sleepiness similar to fine
The main source of these beautiful gems is Achtaragda River mouth, Wilui River Basin, Saha Republic, Eastern-Siberian
Sources for green and pink hydrogrossular are Canada, Russia,
South Africa, and the United States. White Hydrogrossular is found
in Burma and China.