60 
EAST WING. 
General Strontianite (18b), the carbonate of strontium, is the mineral 
Collection of f r0 m which most of the strontium nitrate is made for use in the 
Minerals 
manufacture of fire-works, owing to the fine crimson colour 
which it gives to the flame : it is also much employed in the 
process of sugar refining. 
Cerussite (18b) is the corresponding carbonate of lead, and 
when abundant is a valuable ore of the metal. 
Calcite (18e), carbonate of calcium, is represented by an 
extraordinarily fine suite of specimens, illustrating an almost 
endless variety of crystalline form. The clear variety from 
Iceland is largely used in optical instruments for the polarisa- 
tion of light. 
Chalybite, or Spathic iron ore (20h), is the carbonate of iron 
and is a most valuable ore of the metal. The most important 
English iron ore, Clay iron-stone, is a mixture of chalybite and clay 
Calamine (19h), carbonate of zinc, is an important zinc ore. 
Chessylite (2 Id) and Malachite (22b) are respectively the 
blue and green hydrated carbonates of copper, and are ores of 
that metal. Malachite is found in large masses ; and by reason 
of the high polish which it takes and its beautiful markings, is 
much used for ornamental work of various kinds. 
Passing to the silicates we come to Olivine (22f ), one of the 
less hard and least valued of the precious stones ; when of a 
yellow colour it is known as the Chrysolite, while the pistachio- 
green variety is the Peridot of jewellery. 
Hiddenite (23a), a rare emerald-green variety of spodumene 
discovered a few years ago at Stony Point, in North Carolina 
has been introduced as a precious stone. 
Asbestos (24c) is a variety of hornblende used in the arts ; 
it is found in long fibres, and in some of its varieties is so 
flexible that it can be woven into gloves and other articles. 
The term asbestos, unquenched or unquenchable, was applied 
to the mineral by the ancient Greeks, because, owing to its 
being unaltered by heat, wicks made of it were used in 
maintaining the sacred perpetual fires of their temples. 
Napkins of asbestos were cleaned by being thrown into 
the fire ; asbestos cloth was also used in the process of cre- 
mation to keep the ashes of the body distinct from those of 
the fuel. It is now largely employed for more prosaic purposes, 
