katoite
Rare member of the
Garnet group containing
hydroxyl (OH) in its structure in place of some
silica (SiO
4). Its formula is Ca
3Al
2(SiO
12)
3-x(OH)
4x
(where
x is 1.5 to 3.0) . The mineral Katoite is the same as
Hibschite, but contains less hydroxyl replacing the silicate (In Katoite,
x is 0.2 to 1.5). Hibschite and Katoite are white to light yellow, and only occur in tiny crystals, which may be packed together very densely. Katoite and Hibschite are called
Hydrogarnets, or Garnets with hydroxyl in their structure. They may also be called hydrogrossular, for they are, in essence, the mineral
Grossular with a slight replacement of silica for hydroxyl. Katoite and Hibschite are scientifically classified as individual minerals.