416 Scientific Intelligence. — Mineralogy, 



calcai'eous spar, while the lateral faces are scarcely affected by it. 

 Chemical Composition. — According to Gustav Hose, it appears that 

 this mineral consists of alumina and water, witii a trace of lime, so 

 that in a chemical view it may be arranged with Diaspore and Gibb- 

 site, from which, however, it is distinguished by external characters. 

 It is named Hydrargillite, from vdug water, and a^yiXkog alumina. 

 Geognostic and Geographic Situations. — Occurs near Slatoust in the 

 Uralian Mountains along with magnetic iron-ore. 



7. Sarsowite, anew mineral species. — Description. Colour snow- 

 white. Occurs massive, and in granular distinct concretions. Lustre 

 of the granular varieties feebly pearly, the compact dull. Fracture 

 splintery or imperfect foliated. Translucent on the edges. Hard- 

 ness between that of apatite and felspar. Specific gravity =z. 2.740 

 to 2.752. Before the blowpipe it melts, but only on the edges, with 

 difficulty ; with borax it melts slowly and calmly into a transparent 

 glass. Pounded and heated with muriatic acid, it is easily decom- 

 posed, and forms a thick jelly. Chemical Compositiofi. Lime — 

 18.16 ; alumina = 32.76 ; silicic acid = 49.08 = 100.00. Geog- 

 nostic and Geographic Situations. — Hitherto it has been found only 

 in loose blocks, sometimes several cubic feet in size, in tlie gold sand 

 of Barsowskoj, in the Urals. Blue crystals of corundum, greyish- 

 black grains of zeilanito, and white folia of mica, occur imbedded in 

 it. It is named Barsowite, from its frequent occurrence at Bar- 

 sowskoj. Both externally and in chemical composition, it much re- 

 sembles scapolite, but is distinguished from it by its structure, and 

 by its relations before the bloAvpipe and to acids. 



8. Discovery of the repository (lagerstdte') of the Sun-Stone on 

 the Selenga in Siberia. — The sun-stone is a variety of felspar, which, 

 when viewed in the direction of its chief cleavage planes, displays 

 mmiberless golden spangles, which are distinctly seen in sun-light, or 

 better by the light of a candle, while in other directions it shews 

 only a brown colour. It occurs on the Selenga, forming, with quartz, 

 considerable veins. The sun-stone in these veins, it is believed, may 

 be found in masses sufficiently large to allow of their being fashioned 

 into vases two feet high. These will be of great value, as ring- 

 stones of this variety of felspar sell at a considerable price. 



9. Plumhiferous Aragonite. — This curious mineral occurs in pris- 

 matic distinct concretions, intermixed with lead-glance. Its colour 

 is greenish-grey, and it is translucent on the edges. Specific gravity 

 = 2.977 (at 11° cent.), and 2.986 (at 13° cent.). It is a compound 

 of 95.940 carbonate of lime; 3.859 of carbonate of lead, and water 

 of decrepitation = 0.157 = 99.966. It occurs at Tarnowitz in 

 Upper Silesia. 



10. Tachylite. — This mineral, first described by Breithaupt, from 

 specimens found near Gcittingen, has since been found in the Vogels- 

 gebirge. TIio folbwing is an analysis of a specimen from the latter 

 locality by C. G. Gmelin, silica 50.220; titanic acid 1.415; alu- 

 mina 17.839 ; lime 8.247 ; soda 5,185 ; potash 3.866 ; magnesia 



