Natural Green Hydrogrossular garnet rough with spots of chrome Vesuvianite

compact translucent and crack free material which can be cabbed into high grade cabochons

untreated unheated, from Afghanistan.

rossular is the most varicolored of the Garnets . The term Garnet describes a group name for several closely related minerals that form important gemstones, and Grossular is an individual member mineral of the Garnet group. Pure Grossular is colorless; the wide range of colors in this Garnet is caused by various impurities. Some Grossular types have their own unique variety or trade names, and are only called by these names in the gemstone market. The orange-brown Hessonite and deep green Tsavorite varieties are the best known varieties. In the gem trade, the term Grossularite is synonymous with Grossular, and both names are acceptable names for describing this gemstone.

Hydrogrossular is a calcium aluminium >garnet series (formula: Ca3Al2(SiO4)3-x(OH)4x, with hydroxide (OH) partially replacing silica (SiO4)). The endmembers of the hydrogarnet family (grossular, hibschite, and katoite) depend on the degree of substitution (x):[1]

• grossular: x = 0
• hibschite: 0.2 < x < 1.5
• katoite: 1.5 < x < 3.

Hydrogrossular is a garnet variety in which a Si4+ is missing from a tetrahedral site. Charge balance is maintained by bonding a H+ to each of the four oxygens surrounding the vacant site.

Hydrogrossular is found in massive crystal habit, sometimes grown in with idocrase.[1]

Hydrogrossular is translucent to opaque, and found in green to bluish green, pink, white, and gray. The cause of the green color is chromium, and possibly iron. Pink hydrogrossular is caused by the presence of manganese. Hydrogrossular may have dark gray to black small inclusions.[1] It has similarities to jade, and has the misnomers Transvaal jade , and African jade .[1]

Hydrogrossular is sometimes used as a gemstone, being cabochon cut, or made into beads. Sources for green and pink hydrogrossular are Pakistan and Afghanistan, Canada, Africa, and the United States . White hydrogrossular is sourced from Burma and China