SILICATES. 
87 
such as the lining of iron safes, packing for steam-pipes and 
boilers, and in gas-stoves, for which purposes its low con- 
ductivity for heat renders it serviceable. 
Jade or Nephrite (24d), a much valued mineral, l)elongs to 
the same mineral group as hornblende. The various shades 
of colour and the beautiful polish which this tougli mineral 
will take are illustrated by specimens in the case. The worked 
specimens from ]N"gw Zealand, of which there are se^'eral 
exhibited, are now rare. An immense water-worn mass, 
found some years ago in Asiatic Eussia, is shown in the 
pavilion. 
Meerschaum (23g), the light soft porous mineral used for 
tobacco-pipes, is a hydrated silicate of magnesium. Ser- 
pentine (25a) is another hydrated magnesium silicate : the 
ease with which it is worked and takes a good polish, its green 
colour and varied markings render it much sought for as a 
material for fire-places, tables, and other indoor work : exposed 
to the weather it soon loses its polish. 
Topaz (25d) in its clear varieties is one of the precious 
stones. The crystals from the Urulga river, in Siberia, are 
remarkably fine ; they are of a delicate brown colour, but are 
kept covered, as the action of light speedily bleaches them. 
The yellow crystals from Brazil assume a peculiar pink colour 
when heated, and are then known to jewellers as Burnt or 
Pink Topaz. 
Garnet also belongs to the group of precious stones ; when 
the red is tinged with violet, the stone is the Almandine or the 
Syrian garnet (named after Syriam in Pegu), and when cut e7i 
cahochon, the Carbuncle of jewellery (26f); the Cinnamon- 
stone or Hessonite is yellow (26e) ; the Pyrope and the 
Bohemian garnet are blood-red (26e) ; Uvarovite is a green 
chrome-garnet (26h). 
Jadeite (27a) is one of the green stones which, under the 
name of jade, are wrought into ornaments in China : from 
jade it is distinguished by its chemical composition, structure, 
and higher specific gravity. Among the specimens of Epidote 
(27c) a remarkable suite from the Fntersulzbachthal is ex- 
hibited. 
Mica (28a) is tlie name given to a group rif minerals differing 
