gallery.] natural history. (Minerals.) 69 
quincite, from St. Quintin and from Mehun in the Department de 
Cher, is common opal tinted, as it is supposed, by organic colouring 
matter, in the same manner as the magnesite occurring with it in the 
fresh water limestone of that part of France. 
In the tw r o next Cases are placed the Silicates with one base. 
Case 25 contains the silicates of lime and some of the silicates of 
magnesia and of alumina. To the former belongs the table spar or 
wollastonite from Mount Vesuvius, Nagyag, &c., and the okenite; 
perhaps also the alumocalcite of Breithaupt, before considered as de¬ 
composed opal, from Eibenstock, Saxony. 
The silicates of magnesia comprehend several of the minerals placed 
by Werner in his talc genus:— steatite , or soapstone, the more interest¬ 
ing varieties of which are, that of yellowish green colour from Greenland, 
and that from Gopfersgriin in Franconia, with small crystals of other 
mineral substances, especially quartz, converted into, and forming part 
of the massive steatite ; variety called chalk of Brian^n ;— keffekil, or 
meerschaum, from Natolia, of which the well-known pipe-bowls are 
made, and that from Valecas in Spain ;—also a related substance, 
called keffekillite by Dr. Fischer, who discovered it in the Crimea;—- 
the lithomarge , or steinmarh, has been associated with steatite, although 
most of its varieties are silicates of alumina: the more remarkable of 
which are, that of a reddish-yellow colour in porphyry, from Rochlitz, 
and the fine purplish-blue variety fromPlanitz ( teratolite , formerly 
called terra miraculosa Saxonica), &c— serpentine , the purer varieties of 
which (generally hydrates) are called noble serpentine : they constitute, 
in combination with primitive lime-stone, the verde antico and some 
other fine green marbles; crystallized serpentine, from Snarum, in Nor¬ 
way; —among the varieties of the common serpentine, those best known 
are from Baireuth and from Zoblitz in Saxony, where they are manu¬ 
factured into vases and various other articles; serpentine with embedded 
garnets, magnetic iron-stone, asbest, &c..—Of other substances nearly 
related to serpentine in this Table Case we have, the hydrophite of 
Svanberg; the pierolite; the antigorite ; the villarsite , &c.—With these 
are also placed the metalloid diallage or diallagite , more commonly called 
schiller-spar, from the Hartz, &c.; and some varieties of what is called 
bronzite and xanthophyllite _To the silicates of magnesia is also re¬ 
ferred the olivine, a green granular substance, occurring chiefly in trapp 
rocks, as also in the cells of the meteoric iron of Siberia and Atacama 
(see Tab. 1): when in a pure state and crystallized it is denominated 
chrysolite or peridot, classed with gems; hyalosiderite, batrachite and 
monticellite are also olivine-like substances. 
Case 26. Silicate of zinc, called smithsonite (after the distinguished 
English chemist w 7 ho first explained its nature, and that of silicates in 
general), and also electric or siliceous calamine, the finest specimens of 
which are those from Siberia and Hungary; the variety called willemiie , 
from Aix-la-Chapelle, &c.— Silicate of manganese, of w 7 hich there are 
several varieties (some of them nothing but mechanical mixtures of 
this silicate with carbonate of manganese, and quartz), which have 
received particular names, such as allagite, rhodonite, &c . — tephroite. 
— troostite—Silicate of cerium or cerite, found only at Bastnas, in 
Sweden. — Silicate of iron, to wdiich belong the chlorophceite, chlor - 
opal, stilpnomelane , hisingerite, gillingite , polyhydrite , sideroschizoliie, 
