FIRST FLOOE. 
57 
richest and most varied hues ; when red it is the true Ruby; ^Yhen General 
azure it is the Sapphire ; while the yellow, green, and purple S^^ra^!^ °^ 
varieties are known respectively to jewellers as the Oriental 
Topaz, Emerald, and Amethyst ; the prefix " oriental," though 
at first used to suggest that the stones are not the ordinary topaz, 
emerald, and amethyst, but others of a similar colour coming 
from the East (India, Ceylon, Siam, Pegu, &c.), Avas afterwards 
understood to imply only the excellence of their characters. The 
Star-stones, another variety of corundum, when placed in a 
strong light show a six-rayed star. 
Haematite (11a) is a valuable ore of iron. 
Cassiterite, or tin-stone (llf), is the ore of tin, of which metal 
it contains 79 per cent. 
Zircon (13b), when clear and without flaws, is one of the 
precious stones : one variety with peculiar red tints is the 
Hyacinth or Jacyntli, while the colourless, yellowish, and dull 
green are termed Jargoon : the colourless variety, owing to its 
high refractive power, approaches even the diamond in bril- 
liancy. 
Quartz is the most common of minerals. In its clear and 
transparent variety it is the Crystal of the ancients and the 
rock-crystal of modern times ; it is the Brazilian Pebble of the 
spectacle-makers (14b). After the clear come the smoky varie- 
ties, including the Scotch Cairngorm and Occidental Topaz (14g). 
!N"ext comes the Amethyst (14h), one of the less valuable, though 
one of the most beautiful of the ornamental stones. The 
Quartz Cat's-eye (13f) is a variety presenting the opalescence, 
but not the hardness or the brilliancy, of the true cat's-eye 
already referred to : the opalescence is due to enclosed fibres of 
an asbestos-like mineral in the specimens from Ceylon, and to 
fibres of crocidolite in the blue, and of altered crocidolite in the 
brownish-yellow specimens from South Africa. 
Jasper (13g), an uncrystallised coloured mixture of silica and 
clay, is distinguished from ordinary quartz by its opacity and 
dull earthy fracture. It is of various colours, chiefly red, brown, 
yellow and green ; and the colours are arranged sometimes in a 
nodular form as in the Egyptian Jasper, at other times in stripes 
as in the Pdband Jasper. 
The Lydian- or Touch-stone (15a), by reason of its hardness 
