106 DECHENITE. 



accompanied by Garnet, Mica, Wollastonite, 

 &c. Colour white or yellowish ; inclining to 

 grey when transparent, to whitish when 

 opaque. Lustre inclining to opalescent in 

 transparent, to pearly in opaque specimens. 

 Fracture conchoidal. H. 5 to 5-5. S.G. 24. 



Fig. 142. 



Anahjsis by MonticeUi §■ Covelli ; 



Silica 42-91 



Alumina .... 33-28 

 Peroxide of iron . . . 1*25 



Lime 2*02 



Potash . . . .7-43 



Loss ..... 3-11 



100-09 



BB alone, fuses with effervescence to a 

 somewhat jjorous, opaque, white globule. 

 Gelatinises in nitric acid, with effervescence. 



Name. By MonticeUi and Covelli iu ho- 

 nour of Sir Humphry Davy. 



Davyne may be distinguished from Nephe- 

 line b} the length of its crystals excee ling 

 their breadth, the reverse of which is the 

 case with the latter mineral. Its specific 

 gravitv is also much lower. 



Brit. Muf„ Case 3L 



Dechenite, C. Bergemann. Occurs in 

 small botryoidal masses, with a crystalline 

 texture, and some appearance of a rhombohe- 

 dral cleavage. Colour dull -red; sometimes 

 vellowish. Lustre of fresh fracture greasy. 

 Streak yellow. H. 4. S.G. 6-81. 



Comp, Pb V, or vanadate of lead. 



Analysis by Bergemann ; 



Vanadic acid . . . 46-101 

 Oxide of lead . . . 63-717 



99-818 



BB alone, fuses easily to a yellowish glass ; 

 with soda forms a white enamel containing 

 grains of lead. 



Locality. The Lauter Valley, near Nieder- 

 Schlettenbach, in Khenish Bavaria, in varie- 

 gated (sandstone. 



Name.. After Dr. H. von Dechen, of Bonn. 



Brit. Mus., Case 38. 



Delanovite, Kemigott. A reddish, amor- 

 phous, earthy mineral ; a variety of Halloy- 

 site, placed by Kenngott near Montmoril- 



DELYAUXINE. 

 lonite. Coloured by silicate of manganese. 

 Streak reddish, somewhat shining. Adhert. s 

 to the tongue. Fracture splintery to earthy. 

 H. 1 to 1-5. 



Comp. (IRS + |S) 8:2 + loH. 



Analysis by Von Hauer : 



Silica 50-55 



Alumina . . . . 19-15 



Lime 0-63 



Protoxide of manganese . 4-40 

 Water 24-05 



98-78 



BB infusible. 



Locality. Environs of Nontron, depart- 

 ment of Dordogne in France. 



Dklessite, Naumann. Occurs massive, 

 with a short fibrous or scaly featherv tex- 

 ture, in the amygdaloidal porphyry of 

 Oberstein and Zwickau, in Saxony. The 

 fibres are very delicate, and arranged nearly 

 perpendicular to the surface on which they 

 are implanted. Colour olive-green to 

 blackish-green. In powder always clear 

 green. H. 2-5. S.G. 2-89. 



Comp. (iR + iit) Si| + 1 -5 H. 



Analysis from Planitz, near Zwickau, by 

 Deksse : 



Silica 29-45 



Alumina .... 18-25 

 Peroxide of iron . . . 8-17 

 Protoxide of iron. . .15-12 

 Magnesia .... 15-32 



Lime (1-45 



Water 12-57 



99-33 



BB fuses with difficulty at the edges. 



Soluble in acids, yielding a deposit of silica. 



The variety from Planitz, near Zwickau, 

 contains much more iron than that from 

 Oberstein. 



Delislite, Leymerie. A name for Freis- 

 lebenite after Rome de Lisle, who made it a 

 species, as " Argent gris antimonial." 



Delphinite. a variety of Epidote from 

 Dauphiny. Colou.r olive-green. Clear and 

 transparent. Lustre very brilliant. Takes 

 a fine polish. 



Delvauxene, Delvauxit, Dumont. Is 

 supposed to be a mechanical mixture. It 

 occurs massive and earthy, with a yellow- 

 ish-brown, brownish-black, or reddish colour, 

 and a waxy, dull lustre. Opaque to trans- 

 lucent at the edges. H. 2-5. S.G. 1-85. 



Comp. Fe2 P' + 24H (Dumont), or Fe2 P 



+ 18H (Delvaux). 



