252 Third Supplement to Danas Mineralogy. 



has been analyzed by M. A. Damour and shown to be Chrysolite. He obtained 

 (L'Institut, No. 1148, xxiv, 4, Jan. 1856): 



Si Ti Mg £e Tfcn H 



36-30 530 4965 ' 6t)0 0-60 1-95=99-80 



Oxygen, 18-86 2 11 19-50 179 013 1-73 



The silica and magnesia hare the oxygen ratio 1:1, as in chrysolite. But the 

 exact condition of the titanic acid is not ascertained. [This mode of occurrence of 

 chrysolite is analogous to that of the Boltonite (chrysolite) in granular limestone, 

 and the Glinkite (another variety) in talcose slate. May it be that the titanium is 

 due to a mixture with titanic iron ?— d.J 



Contstonite and Hedplite [p. 465, and Suppl. n]. — According to R. P. Greg, 

 Esq., in a recent letter to the author, these two species, though curious in them- 

 selves, have been found to be artificial. 



Copiaptte [p. 387 and Suppl. i]. — Analysis of fibrous copiapite (stypticite) from 

 Copiapo, Chili, by E. Tobler (Ann. Ch. u. Pharm. xcvi, 383) : Sulphuric acid 3149, 

 sesquoxyd of iron 3169, water 36 82 = 100. 



Coqutmbtte [p. 380]. — Observed rather abundantly by Scacchi about fumaroles 

 after the eruption at Vesuvius in 1855 (op. cit., p. 195). Part of it is in a brownish 

 friable cru^t ; obtained by dissolving the saline crust and evaporating, in brownish- 

 yellow hexagonal crystals. Also as a yellowish crust, in many parts tinged green, 

 compact in texture, and with a very bright lustre in the fresh fracture. 



Cryolite [p. 97 and Suppl. u]. — J. W. Tayler, Esq., has given a description of 

 the mode of occurrence of cryolite in Greenland, with wood cut illustrations, in the 

 Quart. Jour. Geol. Soc. xii, 140. The locality is at Evigtok, about twelve miles from 

 Ark^ut, on the Fiord of that name. The rock is gneiss and granitic gneiss. It is 

 intersected by a vein of quartzrock containing coarsely crystallized feldspar, cryo- 

 lite, and ores of iron, tin, lead, zinc, tantalum, etc., running about southwest, besides 

 other small veins and masses of cryolite ; and to the east and west there is a trap- 

 dvke. The main mass of cryolite forms a bed or vein parallel to the strata, running 

 nearly east and west, dipping S 45°, and is about 80 feet thick and 300 long. It is 

 bounded along the walls by a band of spathic iron, quartz, and in some parts by 

 fluor and galena, while near the walls in the cryolite there are more or less galena, 

 copper and iron pyrites, etc. Tantalite and cassiterite occur in the cryolite. The 

 galena contains 45 oz. of silver to the ton and is worked. In its lower part the 

 cryolite is black, and the white color of the upper part is attributed to exposure to 

 heat. The author infers "that the trap now found at each end of the cryolite has 

 formerly overlain it, heating it superficially and rendering it white." 



CYANOCHROME, Scacchi. — A sulphate of potash and copper, among the pro- 

 ducts of Vesuvius, at the eruption of 1855 (op. cit., p. 191). — In clear blue crystals 

 obtained by dissolving and evaporating the saline crust, from the lava of Vesuvius ; 

 also in azure blue spots upon the white crust. Composition (^K-\-\Qi\x) S-f- 3H. 



Form of crystals monoclinic. C (or inclination of vertical axis) = 75° 30'. 



Occurring planes, O, Vi, 2i, ii, 1, T, 22, 11 O : U = 15° 30', O : K = 153° 56', 

 O : li==141° 47', O : 2i = 116° 49', /: 7=108° 12'. 



Cvanostte [p. 380], — Observed at Vesuvius by Scacchi, among the products of 

 the eruption of 1855. Op. cit., p. 189. 



Analvsis of a specimen from Copiapo, Chili, by E. Tobler (Ann. Ch. u. Pharm. 

 xcvi. 383) : Sulphuric acid 32 41, oxyd of copper 30 77, water (as loss) 36 82= 100. 

 Occurs with stypticite and both results from the decomposition of chalcopyrite. 



Dathoute [p. 334 and Suppl. i, n]. — F. Schroder has made many new measure- 

 ments of Datholite crystals (Pogg. xcviii, 34), and concludes from them that the 

 form is monoclinic, with the inclination of the axis, 90° 7'. He figures a crystal 

 having the planes in the annexed table. 



