1871.] Mineralogy. 133 



from Wolsendorf, in Bavaria,* where it occurs in the form of yellow acicular 

 crystals in druses of quartz encrusting fluor-spar. The crystals, which belong 

 to the rhombic system, contain — Silica, 13*781 ; phosphoric acid, 0*448 ; 

 peroxide of uranium, 16752 ; alumina and ferric oxide, 0*511 ; lime, 5*273 ; and 

 water, 12*666. 



Excellent information on the mines and minerals of Elba — an island to 

 which we are indebted for those wonderful specimens of specular iron-ore, 

 iron-pyrites, and lievrite, which grace the cabinet of every mineralogist, — will 

 be found in Von Rath's recently-published mineralogico-geological essay on 

 that island, f 



Gustav Rose has shown £ that in iron-pyrites and cobaltine a close relation 

 exists between the hemihedral forms of the crystal and their thermo-electric 

 properties. The same author announces the discovery of zircon in the hyper- 

 sthenite of the Radauthal in the Hartz.|| Dr. Scharff has published a crystallo- 

 graphic paper in which he seeks to determine what influence twin-growth 

 exerts upon crystals of calcite.§ 



So full of interest are the volcanic rocks which occur in the neighbourhood 

 of the Laacher See, in the Eifel, that they have often courted investigation by 

 the mineralogist and geologist. We need not, therefore, do more than call 

 attention to a series of papers in course of publication by Herr Dressel, whose 

 long residence at the Abbey of Laach has given him more than usually good 

 means of observation. His first contribution deals with the trachyte of 

 Laach. % 



The Townshend Jewels. — Much scientific as well as artistic interest centres 

 about many of the minerals which have been used for purposes of ornament. 

 The study of the intruding substances and the cavities often occurring in 

 quartz, ruby, and topaz, has led to the discovery of many singular facts, and 

 has partially lifted the veil which shrouds from curious eyes the origin of some 

 of the most beautiful products of the earth. So also the crystalline forms and 

 optical properties of precious stones, together with the action of heat and other 

 forces upon them, have afforded ample and profitable materials of research for 

 the mathematician and the physicist. Thus it would be easy to vindicate the 

 claims on scientific consideration which jewels possess. Were we to travel 

 for a moment out of the path which we intend to follow in the present notice, 

 and to speak of the artistic qualities of precious stones, we should have a 

 rather difficult task to accomplish, for strange to say, it has become usual, 

 amongst a certain clique of artists and connoisseurs, to depreciate their beauty. 

 Professor Ruskin,** for example, talks of the colours of gems as " entirely 

 common and vulgar;" he calls the green of the emerald as "vulgar as house- 

 painting," and states (what is absolutely incorrect) that " no diamond shows 

 colour so pure as a dewdrop." " The ruby," he adds, " is like the pink of an 

 ill-dyed and half-washed-out print compared to the dianthus." Other writers 

 on art, ignorant of those wondrous properties of jewels which are developed 

 only by judicious cutting, would not allow a specimen to be facetted, but 

 simply rounded and polished in the way known as en cabochon. Our present 

 purpose, however, is not to offer a logical justification of the fondness for 

 precious stones, which most people exhibit to some degree, but to direct the 

 attention of our readers to the superb suite of specimens which has been 

 recently bequeathed to the nation by the late Rev. C. H. Townshend. The 

 collection is to be seen in the South Kensington Museum, and is, or was 

 recently, in one of the picture galleries. A cataloguef f of the specimens has 

 been published under the auspices of the Science and Art Department, but, 



* Leonhard's Jahrbuch, 1870, p. 780. 



+ Zeitsch. d. Deutsch. Geolog. Gessell, xxii., 1870, p. 591. 



t Monatsbr. d. k. Akad. d. Wissensch., Berlin, 1870. 



II Zeitsch. d. Deutsch. Geolog. Gessell, xxii., 1870, p. 754. 



§ Leonhard's Jahrbuch, 1870, p. 542. 



*ff Ibid., p. 559. 



** Ruskin's Le&ures on Art, pp. 176 and 177. (1870). 



++ Catalogue of Gems and Precious Stones [Townshend Bequest], by J. Tennant. (1870). 



