A green mineral of the smectite group that is a hydrated basic nickel silicate and belongs to the hexagonal crystal system.

= picrolite n.

A hydrous silicate of iron and aluminium, occurring in thin scales, or as a velvety coating, of a black or bronze colour.

A mineral of uncertain identity, consisting of hydrated magnesium aluminosilicate and resembling serpentine.

An yttrium silicate, Y3Si3O10OH, found as translucent monoclinic crystals.

A triclinic silicate of barium, BaSi2O5, which occurs as white or colourless plates at a locality in California, and has been artificially prepared.

A basic orthorhombic silicate and fluoride of niobium and calcium, (Ca,Nb)4Si(O,OH,F)9, which occurs as yellow crystals.

Mineralogy. A rare mineral of the zeolite class occurring as fibrous white crystals, typically as an alteration product of acid lavas.

A yellow-brown complex silicate of barium, near Ba4Ti3½Si4O18(OH)1½.Na2SO4, found as tabular crystals in pegmatites in the Inagli massif, Yakutia…

A blue mixed-layer clay mineral (see quots.).

A rare, bright green, monoclinic mineral of the serpentine group, consisting of a basic silicate of nickel, Ni3Si2O5(OH)4, found originally as a…