260 



Third Supplement to Bands Mineralogy, 



[Figure 1 is derived from Greg's figure. It represents the crystal flattened par- 

 allel to I. Figure 2 is the normal form of the crystals, and corresponds closely 

 to Dauber's crystals as represented by him. 



It remains to be ascertained whether there is any Rhodonite with a monoclinic 

 form ; in other words, whether Fowlerite or Paisbergite is not true Rhodonite.] 



Sal-ammoniac [p. 92.] — Reported by Scacchi as formed at Vesuvius at the erup- 

 tions of 1855, but, as usual, where the lava has spread over soil with vegetation. It 

 sometimes presented the form of the rhombic dodecahedron with cavernous faces s 

 in 1850, it occurred in twins. 



Salt [p 90, and Snppl. ii,] — Announced by Scacchi as among the products of the 

 Vesuvian eruption of 1855, (Op. cit., p 183,) occurring at a small cone of erup- 

 tion, in small cubes, incrustations, stalactites. Some cldorid of potassium, and also 

 sulphate of potasm exists with the common salt in the stalactites. Scacchi also 

 announces the probable occurrence of chlorid of magnesium in the saline crusts, 

 together with the chlorid of manganese. The last was detected among the saline 

 products of the eruption of 1855 (op. cit., p. 181.) It was detected in the crust by 

 treating it with distilled water and testing with ferrocynnid of potassium, when the 

 white precipitate thrown down acquired after a while a pale rose tint. Other 

 trials also were made. 



Serpentine fp. 282, 511 and Suppl. i, n.J— The Serpentine Rock of Roxbury and 

 other places, Vermont, has been analyzed by A. A. Hayes (Proc. Bost. Soc N H., 

 Dec. 1855, and July 1856, and Am. J. Sci., xxi, 382), and shown to consist largely of 

 carbonate of magnesia; ihe associated white spar is this species pure. He regards 

 the rock as made up of this carbonate along with different silicates. An average of 

 the rock of Roxbury afforded 38 00 of the carbonate and 62 00 of associated min- 

 erals. The rock of Proctorsville, Vt., gave 33 45 of ifrg C, leaving 66 55 for the 

 re< consisting of Si 3610, Mg 18'70, Fe, Mn, O, 3 40. AM 1 "13, chromic iron 0 92, 

 S 6 21=99 91. In another specimen of the same, the proportions of magnesite to 

 the rest was 26 40 : 73-60. — The magnesite is attacked by muriatic acid with great 

 difficulty. 



The same serpentines had been previously examined by Dr. Jackson, who states 

 and still holds (Proc. Bost. Soc. N. H., Feb. and July, 1856) that excluding the veins 

 and some admixture of carbonate of magnesia, the serpentine has the usual compo- 

 sition, being a hydrous silicate of magnesia. 



Silver [p. 15]. — A few filaments of native silver observed at a copper mine a 

 mile from the Cheshire barytes mine, Ct. — S. Smith, in Proc. Amer. Assoc., ix, 188. 



Smithsonite [p. 447, and Suppl. i] — Pseudomorphs of Smithsonite having the 

 form of dolomite, have been observed at the Lancaster zinc mines. — W. J. Taylor, 

 Am. J. Sci., [2], xxi, 427. 



Sphene [p. 268J. — A pulverulent decomposed sphene affording; reactions for water 

 (12 5 per cent) and titanic acid, has been named Xanthitane by C. U. Shepard (Am. 

 J. Sci. [2], xxii, 96). The color pale yellowish white ; lustre feeble ; brittle ; hard- 

 ness as 3 - 5 ; G = 2 - 7 — 3 0. No analysis has been made. Found in a decomposing 

 feldspar, associated with zircon, at Green river, Henderson Co., N. C. 



Stannite fp. 512.] — Analysis by Bischof (Chem. u. phys. Geol., ii, 2026). 



Si So 3fcl Ve Ca ign. 



5157 38-91 4 53 355 0 16 043 = 991 5 



It appears hence to be a mixture of different substances. It is probably a pseudo- 

 morph after feldspar, in which tin ore has replaced much of the original ingredients. 

 It occurs massive, with a small conchoidal fracture. 



Staurotide [p. 261]. — Found at the Lead mine. Canton, Georgia, in the quartz or 

 quartzose mica slate which is the gangue of the vein, sometimes penetrating the 

 pyrites and copper ore. The crystals are "rarely thicker than a large-sized needle." 

 Prof. Shepard says that they appear to be identical with the Partschin of Haidinger, 

 (see Suppl. r) [but partschin is a very different mineral from staurotide, having the 

 garnet oxygen ratio.] 



