78 PHYSIOGRAPHY. 



Blue Vitriol Boltonite. 



3. Blue Vitriol owes is existence to the decomposition of Copper Pyr- 

 ites; and is found dissolved in water issuing from mines, and which has 

 received the name of Water of Cementation. From this, it deposits itself 

 spontaneously in certain places, and presents itself in large masses, occa- 

 sionally associated with other ores. 



4. Its chief localities are the Rammelsberg near Goslar, Neusohl in 

 Hungary, Anglesey in the Pary's mine, Cornwall at the Consolidated 

 mines, and at the copper mines in Wicklow, Ireland. Its occurrence 

 maybe expected at the copperas mine in Stafford, (Vt.) 



5. As it occurs in nature, it requires first to be purified, before it can 

 be employed in the arts, where it is used in dyeing, in printing of cot- 

 ton, linen, &c. The oxide of copper, separated from its acid, is likewise 

 used in painting. 



BOLTONITE. Parachrose Tabular- Spar. 



Massive. Composition granular .: individuals large. 

 Cleavage in one direction pretty distinct, in two others ob- 

 lique to the first, indistinct, but affording indications of a 

 doubly oblique prism for the primary form. Fracture un- 

 even or small conchoidal. 



Lustre vitreous. Color bluish grey, yellowish grey, wax 

 yellow to yellowish white. The darker colors change to 

 yellow on exposure to the weather. Streak white. Trans- 

 parent or translucent. 



Hardness = 5-0 ... 6-0. Sp. gr. = 2-8 ... 2*9. 



1. This mineral when first discovered was regarded as Pyrallolite. It 

 is believed to be identical with the substance described by Dr. THOM- 

 SON, (Ann. Lye. Nat. Hist, of N.York, Vol. III. p. 50,) under the name 

 of Bisilicate of Magnesia ; and accordingly the analysis there given is 

 here quoted. 



2. Alone before the blow-pipe, it becomes white and transparent, but 

 does not melt. With borax, it dissolves slowly into a transparent glass. 



3. Analysis. 

 By THOMSON. 



Silica .... 56-64 



Magnesia .... 36-52 



Alumina .... 6-07 



Protoxide of iron .... 2'46 



