416 Progress in Science. [J u ty> 



edges of twin lamellae. He has since shown that the common icositetrahedron 

 of leucite is really a combination of the 16 faces of the ditetragonal octa- • 

 hedron with the 8 faces of the primitive octahedron — four of these being above 

 and four below the faces of the ditetragonal pyramid. Leucite is thus brought 

 within the group of these minerals so characteristic of Vesuvius, which 

 crystallise in the pyramidal system — a group which includes zircon, hum- 

 boldtilite, meionite, vesuvian, and sarcolite. 



It has long been known that diamonds of some size occur in the gold fields 

 of California, and Prof. B. Silliman had suggested that they might be found in 

 the heavy sands from the sluices of the hydraulic washings. This suggestion 

 has lately been verified.* A parcel of sand, taken from the tailings in one of 

 the sluices of the Spring Valley Mining Claim, Cherokee, has been subjected 

 to a searching microscopic examination by Prof. Silliman. This examination 

 has shown that the sands abound in beautiful colourless crystals of zircon, 

 associated with crystals of topaz, fragments of quartz, and granules of chromite 

 and titanic iron ore. But in addition to these minerals, there are a few small 

 masses of a very highly refractive substance, believed from its chemical and 

 physical characters to be true diamond. 



Bauxite — the mineral which has long been employed in the manufacture of 

 aluminium — is used by Dr. C. W. Siemens for lining the rotary furnaces in 

 which he produces iron and steel direct from the ore. According to Mr. Riley, 

 large supplies of this mineral are likely to be yielded by the deposits of 

 aluminous iron ores in the north-east of Ireland. 



Some time ago we had occasion to mention the discovery of some new 

 minerals containing uranium at the Weisser Hirsch Mine, near Schneeber, in 

 Saxony. Dr. Clemens Winkler has published, in a recent number of the 

 " Journal fiir Praktische Chemie," the results of his analyses of these minerals. 



Some confusion has arisen between the two species amblygonite and monte- 

 brasite, but the distinction has been clearly established by Des Cloiseaux. In 

 1862, a mineral was found at Hebron, in Maine, U.S., and referred to the species 

 amblygonite ; in 1870 a mineral was found at Montebras, in France, and named 

 Montebrasite. Now it has since turned out that the original mineral from Monte- 

 bras is merely amblygonite, but a second species has been found in this locality 

 to which the name of Montebrasite has been transferred ; and it is now proved 

 that the so-called amblygonite from Hebron is really this true Montebrasite. 

 The matter therefore stands thus : two minerals are found at Montebras — one 

 called montebrasite and the other amblygonite ; the former is also found at 

 Hebron in the United States, and the latter occurs also at Penig, in Saxony. 

 Montebrasite contains lithia but no soda, and also contains a notable pro- 

 portion of water ; amblygonite contains both soda and lithia, but no water. 



Axinke is one of those doubly-oblique minerals whose crystalline forms, so 

 difficult to the student, have been carefully worked out by several crystallo- 

 graphers. Herr Hessenberg has lately examined the axinite from Botallack, 

 in Cornwall, and has discovered two forms new to this species. His paper is 

 well worth thoughtful reading, for the sake of his sensible remarks on the use 

 and abuse of crystallographic symbols. 



Some observations on the celestine, or sulphate of strontia, of Riidersdorf, 

 and of Mokattam near Cairo, have been published by Herr Arzruni. He has 

 also analysed specimens of celestine from several typical localities with the 

 view of observing the effect of isomorphous replacements on the crystalline 

 form of the species. 



The new species Pucherite — a vanadate of bismuth, from Schneeberg, in 

 Saxony — has formed the subject of a careful crystallographic study by Herr 

 Websky. It appears that the forms of pucherite admit of comparison with 

 those of brookite. 



Fluor-spar must be reckoned among those crystallised compounds, which, 

 though abundant enough in nature, have not hitherto been artificially prepared 



* " Chemical News," May 2nd, 1873, p. 212. 



