Miscellanies. 387 



6. Violan, a silicate of alumina, magnesia, lime, much protoxide of 

 iron and soda, and occurring at Piedmont with manganesian epidote ; has 

 waxy lustre, deep violet blue color, nearly conchoidal fracture, amor- 

 phous, opaque, uneven, brittle, sp. gr. 3.233, does not change on heat- 

 ing, but may be brought by a higher temperature to a clear bead. 



7. Tombacite, an arsenical nickel ore, with a little sulphur, and 

 small trace of iron or cobalt, occurring near Lobenstein in Voigtland ; 

 in color it resembles the magnetical iron, sometimes with a greenish 

 brown hue ; its streak is black, appears to belong to the hexahedral 

 system, is brittle, non-magnetic, sp. gr. 6.637. 



8. Hepatic blende, a mineral mostly wax-yellow, from Saxony, in 

 the mine Hochmuth near Geier, Himmelreich-Erbstollen, between 

 Marienberg and Wolkenstein, and also from Cornwall. The color varies 

 from pea yellow to pink brown, transparent ; the streak is either col- 

 orless or yellowish gray, forms botryolitic and reniform conglomerates, 

 fracture conchoidal, and a sp. gr. 3.7 to 3.78, and, according to Platt- 

 ner's experiments, is said to be a sulphocarbonate of zinc, it containing 

 zinc, sulphur, and carbon. It decrepitates on heating, yielding water 

 and a little sulphur, smells like sulphui'etted hydrogen, and then like 

 coal tar, and then becomes gray ; it is decomposed by hydrochloric 

 acid, disengaging sulphuretted hydrogen ; the gray substance remaining 

 from before is soluble in nitric acid, leaving sulphur and carbon, the 

 first of which may be sublimed and separated. 



It may be inferred from the exf^eriments of Plattner, that this mineral 

 consists of sulphuret of zinc formed by water, and intensely mixed with 

 bitumen or other carbonaceous compound ; for it is not to be presumed 

 to contain any carburet of sulphur, which would in those instances distil 

 over unchanged, unlike the above. 



Hess has described a new mineral, which he calls Volborthite, consist- 

 ing of vanadiate of copper, of yet undetermined degree of combina- 

 tion. It forms crystalline needles of olive green color, papillary ; is 

 translucent in splinters, has a yellowish green streak, and a sp. gr. 3.55 ; 

 on heating grows black, yields a little water ; it melts before the blow- 

 pipe, and by increased heat yields a slag like graphite, extending upon 

 the charcoal with some metallic copper ; by soda the copper is redu- 

 ced instantly, and vanadious soda is formed. 



Gigantolite* by Nordenskiold, from Tammela, Finland. One of the 

 crystals of that mineral measured two and a half inches in diameter. 

 This mineral resembles the Fahlunite, and all the harder varieties of 



* What name could we give to our gigantic crystals of beryl, topaz, apatite, 

 tourmalines, zircon, rhomb-spar, lead, fluor-spar ; the four latter from the State of 

 New York, some of which measure twelve to fifteen inches in diameter? 



