164 NATURAL HISTORY. [NORTH 
or uran-ochre, and the hydrous protoxide of the same, called pitch- 
ore. 
Case 18. Oxide of tin or tin-stone , divided by Werner into 
common tin-stone and wood-tin: among the specimens of the former 
(chiefly from Cornwall, Saxony, and Bohemia) may be specified the 
greyish-white crystals resembling scheel-ore or tungstate of lime, the 
regular and macled crystals, the pebble-like and granular tin-stone 
(shoad-tin, stream-tin, grain-tin, &c.), the columbiferous oxide of tin 
from Finbo in Sweden; a variety of fibrous oxide or wood-tin, com¬ 
posed of radiated-fibrous small globules, and marked with concentrically 
disposed brown and yellow colours, is called toad’s eye wood-tin, &c. 
In the next Case begin the oxides of electro-negative bodies, and 
their various combinations. 
Case 19. Alumina and Aluminates. To the former belongs the 
corundite, divided into noble and common . corundite, the former com¬ 
prehending the precious stones commonly called oriental gems (the 
sapphire, ruby, oriental amethyst, oriental topaz, oriental emerald), of 
the crystallized forms of which the principal modifications are here 
deposited; the latter, to which the name of corundum is more espe¬ 
cially applied, affords one of the hardest and best polishing materials 
to the lapidary: from Bengal, Mysore, China, the Carnatic (Werner’s 
diamond spar), Lapland, Piedmont, &c. As appendix to these are 
added, th efibrolite, (bournonite of Lucas,) one of the concomitant sub¬ 
stances of the common corundum of the Carnatic;—the indianite of 
Bournon, being one of the matrices of the same corundum;—the 
emery , w T hich ow 7 es its hardness and consequent usefulness in polishing 
to an admixture of blue corundum.—The diaspore and the gibbsite : 
both hydrates of alumina. 
Aluminate of magnesia —the spinel: among its principal varieties 
may be specified the blue spinel of Aker in Stidermannia, and the 
brown, often in crystals of considerable dimension, from New Jersey. 
The ceyhnite or pleonaste, and the automolite (also called gahnite), 
from Fahlun in Sweden and from Franklin in New Jersey, are, the 
former an aluminate of protoxide of iron and magnesia, the latter an 
aluminate of zinc;—the chrysoberyl or cymophane , considered as an alu¬ 
minate of glucine and of iron, among the specimens of which may be 
specified the large crystals from the Ural and from Brazil, those in a 
matrix of quartz and feldspar with garnets, from Haddam in Connec¬ 
ticut, and also those from Saratoga and New York;—the mineral called 
gum-lead (plomb gomme ), from Huelgoet in Brittany : a hydrous alu¬ 
minate of lead. 
The five following Cases contain the acid or oxide of silicium (silica, 
quartz), the numerous varieties of which, formerly considered as so 
many distinct species, are mostly indebted for their generally very 
striking external characters to the admixture of matter foreign to the 
species, or to other casual circumstances that prevailed at their formation. 
Case 20. Amethyst quartz of various tints, in grouped crystals, &c. 
—Rock crystal: various modifications cf crystalline forms: small 
dodecahedral and other crystals, known by the names of Gibraltar 
diamonds, Bristol diamonds, &c. ; varieties of colour, according to 
which this substance obtains the familiar denominations of smoky topaz 
or morion, cairngorm, citrine, &c. ; specimen of rock crystal enclosing 
