GEOLOGY A>"D MINERALOGY. 553 



C. Estimated by Pend tments upon and beneath the Earth's 81 r 



7. By Airy, (Astronomer Royal) 6.566 



8. Do. Do. (computed by the Rev. G. H. Haugkton) 5.480 



MIXER ALOGICAI. NOTICES. 



Lake Superior Copper. — M. EFautefeuille (Comptes Rendus, July 21, 1856) has 

 detected the presence of Mercury iu the argentiferous copper of Lake Supe 

 A sample of 200 kilogrammes, shewed, according to his analyses, the following 

 composition : 



Copper ] :;. 



Silver 1 . . . 



Mercury 0.1 



Veinstone 50.496 



200.000 



Staf —The so called compact boracite, from the salt beds of Stafcfurt, 



near Magdeburg, is considered by G. Rose (Pog. Auu. 1S56, Xo. 5) to be distinct in 

 its crystalline structure from the ordinary or monometric boracite, although ac- 

 cording to Karsten's analysis it agrees with this in composition. It dissolves, 

 however, with rapidity in heated hydrochloric acid (the solution depositing hy- 

 drate J BO 3 on cooling;) aud it fuses likewise with great ease. These effects may 

 arise, nevertheless, from admixtures. G-. Rose has bestowed upon it the name of 

 Staasfurtite, but its assumption as a distinct species is at least premature. 



illite. — A soluble substance occurring with the above, has been ai 

 by Oesten in the laboratory of H. Rose. In its composition it is essentially a dou, 

 ble chloride of potassium aud magnesium after the formula (K CI + 2 Mg CI) 

 + 12HO. H. Rose has named it Carnallite, in honor of Herr Von Carnall, of the 

 Prussian mines. 



Tachhydrite. — Rammelsbcrg has examined a kindred salt from the same locality 

 as the above. His analysis leads to the formula (Ca. CI. + 2 Mg. CI.) + 12HO 

 He has called the substance Tachhydrite, in allusion to its rapid deliquescence 

 when exposed to the air. It occurs in rounded yellow masses, transparent to 

 transludeceut, and distinctly cleavable in at least two directions. 



Voigtite. — This mineral (see above, p. 484) is named after M. Voigt, of the 

 Saxe-Weimer mines. 



Leucophane and Melinophane. — Rammelsberg CPog. An. 1856, No. 6) has ana- 

 lysed specimens of these minerals, and proved their mutual identity. He deduces 

 from his analyses the formula Na Fl + (3 CaO, 2 SiO 3 + Be 2 3 , SiO 3 .) For 

 descriptions of these substances, see Dana's System of Mineralogy, 4th Ed., vol. 2, 

 p. 182-3. 



Vanadinite. — Rammelsberg ha- also given an analysis (with notice of the crys- 

 talline form) of Vauadioite from the limestooe of Mount Ovir, near "Wiudisch — 

 KapjM.l in Carinthia. The sub>tance is Momorphous with the pyromorphite group 

 f mineral- id. Prism oo Z, on pyramid oo" = 130° ; oo" over 



polar edge =142" 80 1 ; a (vert, axis.) to ~, as deduced from the latter augle=727 

 : l-ft Sp. gr. =6-886. Formula, as given by Rammelsberg, [Pb CI + 3 (3 FbO 



1' 



