98 COVELLINE. 



brilliant. Fragile. Fracture slightly la- 

 mellar. H. under 5. S.G. 2-69. 



Comp. According to Dvfrenoy : Silica 

 o2-37, alumina 24-02, lime 11-85, magnesia 

 1-40, potash 5-52, soda 3-96 = 98-55. 



B8 fuses to a white enamel. 



Not affected by acids. 



Fig. 134. 



Localities. This mineral was noticed b}' 

 Charpentier, in the defiles of the valley of 

 Seix in the Pyrenees, called " Des Couze- 

 rans," whence the name Couzeranite. It 

 has been referred to Labradorite; but R. P. 

 Greg suggests that it is a variety of Di- 



Biit. Mus., Case 30. 



CovELLiNE, heudant : or Covellinite. 

 Hexagonal. Colour indigo-blue; with sub- 

 metallic, somewhat greasy lustre, a little 

 pearly on the cleavage- face. Streak black, 

 shining. Opaque. Sectile : thin leaves 

 flexible. H. 1-5 to 2. S.G. 3-8 to 3-85. 



Comp. -6-u S2 = copper 66-5, sulphur 33 '5 

 = 100. 



Analysis from Vesuvius, by Covelli : 

 Sulphur . . . .32 



Copper . . . . .66 



98 



BB before becoming red-hot, burns with 

 a blue flame, and melts with ebullition to a 

 globule, which, with soda, yields a button 

 of copper. 



Sokible in nitric acid. 



Localities. — English. Huel IMaudlin in 

 Cornwall: investing Copper Pyrites — Fo- 

 reign. Leogang in Salzburg. Keilee in 

 Poland. Sangerhausen in Saxony. Mans- 

 feld in Thuringia. In black or greenish-blue 

 incrustations around the fumaroles of the 

 crater of Vesuvius, in the form of a sooty 

 deposit, or net-work like a spider's web. 



Name. After its discoverer, Signor Co- 

 velli of Naples. 



M.P.G. Principal Floor, Wall-ca?e 17. 



Craie de Briancon. a subschistous 

 kind of Talc, of a wliitish colour and with a 

 scaly texture. It is composed of an inti- 

 mate mixture of scaly Talc and Steatite ; and 

 is met with in the neighbourhood of Brian- 

 con, Derst. of the Hautes- Alpes, in France. 



Ceaitonite. See Grichtonite. 



CRISTATED QUARTZ. 



Crayon Rouge, Brochant. See Red 

 Chalk. 



Crednerite, Rammelsherg. Oblique. 

 Occurs foliated-crvstalline. Colour steel- 

 grev to iron-black. Lustre metallic. Streak 

 brownish-black. H. 4-5. S.G. 4-9 to 51. 



Comp. Cu5 iM:n2 = oxide of copper 42-9. 

 peroxide of manganese 57-1 = 100. 



Analysis from Friederichsrode, by Ram- 

 melsherg : 



Protoxide of manganese . 64-24 

 Oxide of copper . . . 23-73 

 Barvta . . . .201 

 Oxygen . . . . 8'83 



98-81 



BB infusible, except on thin edges : with 

 borax gives a dull-violet coloured glass. 



Locality. Friederichsrode. 



Name. After Charles Auguste Credner, 

 professor of theology at Giessen. 



Brit. Mus., Case 13. 



Crichtoij^ITK, Bournon, Hnidinger. A 

 Titaniferous Iron occurring in small acute 

 rhombohedrons, having their summits re- 

 placed, and being otherwise variously modi- 

 fied by secondary planes. Colour bluish- 

 black, with a brilliant metalHc lustre. O- 

 paque. Streak deep black. Fracture con- 

 choidaL H. 6. S.G. 4-79. 



Fig. 13.5, 



Comp. *i F-e. 



Analysis by Marignac : 

 Titanic acid . 

 Peroxide of iron , 

 Protoxide of iron . 



. 52-27 

 , 1-20 

 . 46-53 



100-00 

 BB alone infusible; with salt of phosphorus 

 affords a glass, which becomes red on cool- 

 ing. 



Locality. This variety of Ilraenite is found 

 at St. Christophe, near Oisans, in Dauphine, 

 on Rock Crystal, and associated with Ana- • 

 tase. 



Name. In honour of Dr. Crichton. 



Brit. Mus., Case 37. 



Cr'ispite, Saussure. See Rutile. 



Crlstated Quartz. Cellular Quartz 

 with the plates arranged in a cristated 

 manner, like the comb of a cock. 



