41& Scientific Intelligence, 



6. Minercdogical Optical Notice by Bahinet. — Hyalite cut 

 in any direction into plates with parallel faces, and brought 

 between two crossed tourmalines, depolarises light completely. 

 By this character it is distinguished from mUkopal and Mexi- 

 can fireopal. 



7. Malthacite, a new Mineral Species. — Malthacite (from 

 ILaK^a.-/.o<;, fat, which it resembles) was found by Tormer among 

 decayed blocks of basalt near Steindbrfel, between Lobau and 

 Baudissin. Colour white or yellowish ; lustre glistening and 

 resinous ; translucent ; occurs in thin splinters, rarely mas- 

 sive ; fracture uneven, conchoidal ; easily frangible ; feels 

 greasy ; falls into pieces in water. According to O. Meissner 

 it is composed of silica, 50.2 ; alumina, 10.7 ; lime, 0.2 ; oxide 

 of iron, 3.1 ; water, 35.8. Its formula nearly FS^-|-3AS*+5 

 Aq. Decrepitates before the blowpipe, affords water, but does 

 not melt. 



8. Serpentine Crystals of Snarum in Norway. — Quenstedt 

 is of opinion that the mineral resembling steatite, found at 

 Snarum in crystals, imbedded in serpentine, and whose form 

 is identical with that of olivine or chrysolite, is decomposed 

 olivine. Tamnau (in Poggendorff's Annalen, 42, p. 462,) con- 

 siders this opinion as very improbable. He suspects that the 

 after or supposititious crystals are rather formed by the decay- 

 ing olivine being carried away, and the hollows thus left being 

 tilled up with the same substance which forms the surround- 

 ing rock, namely the Serpentine. 



9. Opaline- Allophane. — Schrotter (Poggend. Annalen, 40, 

 p. 380) has analyzed a mineral found at DoUenberg, near 

 Frauenstein, in the Brucker Circle, which he names opaline- 

 allophane, and which occurs in nests between mountain-lime- 

 stone and clay-slate. Its characters are as follows : — Colour 

 bright emerald-green, passing by degrees into bright brown. 

 Exhibits no determinate structure or cleavage ; lustre vitre- 

 ous ; semitraiisparent ; affords a white streak — sp. gr.=1.985 

 to 2.016 ; before the blowpipe is infusible, either alone or 

 with soda, and consists of silica, 11.95 ; alumina, 46.30 ; oxide 

 of iron, 2.95 ; lime, 1.30 ; sulphuric acid, 0.78 ; oxide of cop- 

 per, 0.25 ; water, 36.20 = 99.73. Hence the formula is 



