262 



Third Supplement to Dana's Mineralogy. 



having traces of a basal cleavage. These crystals show no distinct traces. Color 

 brownish -black. Lustre between submetallic and waxy. Thin splinters a yellow • 

 ish brown translucence on the edge. Streak pale grayish brown. H=60. G=5 555 ; 

 another piece 5 100, which is below that of fergusonite for which Allan obtained 

 5 838, and Turner 5 800. The tyrite strongly decrepitates before the blowpipe 

 while the fergusonite only very slightly so. 



The evidence from form and most of the physical characters is so strong that we 

 can hardly doubt the identity. 



URDITE, D. Forbes and T. Dahll (Nyt. Mag. f. Nat. xiii).— Occurs in granite 

 near Notero in Norway. Crystals clinohedral. Color yellowish-brown to brown ; 

 streak pale gray ish -yellow. Lustre greasy. Subtranslucent. G-. of a fragment of a 

 crystal 5-204, 5-19, 5 - 26. In a tube no water. BB. infusible, but glows and color 

 becomes darker on cooling ; with borax in the reducing flame, a glass which is yel- 

 low, somewhat greenish while hot, and colorless on cooling ; with salt of phospho- 

 rus, a skeleton of silica. No reaction of titanium or manganese. On charcoal 

 affords a white metal (tin ?). Powder not attacked by hot muriatic acid. 



According to E. Zschau, (letter addressed to G. J. Brush, dated Dresden, March 9, 

 1856,) the Urdite has the form of monazite, and is that species; he states that he 

 has recognized the planes of Monazite, 1, ii, -li, -1, O, 2i, and 22 [see Min., p. 402.] 

 The crystal is about an inch in length and breadth, and half an inch in thickness ; 

 its weight 20 5 grammes. It occurs in feldspar (in granite intersecting gneiss), and 

 also enveloped in orthite. 



Vanadintte [p. 362, and Suppl. i'].— According to Rammelsberg. (Monatsb. Preuss. 

 Akad., March 1856, 153), the Vanadinite of Mt. Obir near Windisch-Kappel in Ca- 

 rinthia, affords for the angle of pyramid (1:1 over terminal edge) 142° 30'. The 

 same angle in mimetene, according to G. Rose, is 142° 7'; in pyromorphite, 142° 

 15'; in apatite, 142° 20'. Hence phosphoric and vanadic acids appear to be 

 isomorphous. 



Vivianite [p. 415]. — Analyses of earthy vivianite (Eisenlasur), by H. Struve 

 (Bull. St. Petersb., Class. Phys.-math., xiv, 171-173): 



P* £e te fl 



29 17 21 34 21-54 2750 == 99-55 



19-79 33 11 13 75 26 10, Mg 7-37 = 100-12 



Found in crystals, perfectly colorless when first obtained, in the greensand, near 

 Middletown, Newcastle Co., Delaware. — Prof. J. C. Booth in lit. 

 Observed in human bones. — Nickles, Am. J. Sci., [2], xxi, 402. 



VOIGTITE — This new mineral, described by E. E. Schmid (Pogg. xcvii, 108), is 

 from Ehrenberg, near Ilmenau. It resembles a mica, and is disseminated in granite, 

 replacing true mica. The granite is partly graphic granite. In oblong scales, sel- 

 dom over 1 millimeter thick, micaceous in structure ; color leek green, and thin 

 scales translucent, though often yellowish or brown and opaque from alteration ; 

 lustre pearly; hardness somewhat above 2; sp.gr. 291. In a glass tube yields 

 water, exfoliates, and becomes dark brown and metallic in lustre. BB. fuses easily 

 to a black glass; and gives the reaction of iron. Attacked by cold muriatic acid, 

 giving a yellow solution, and the insoluble part becomes after a few days colorless. 

 Composition : 



Si £1 £e Fe Mg Ca Na ft 

 33-83 13-40 8-42 23*01 7*54 2 04 0*96 9-87=99-07 



giving the formula R 3 Si -f- B Si + 3ft, which is that of Biotite, excepting the 

 water. 



The name Voigtite is in honor of M. Voigt, director of the mines of Saxe Weimar. 



[A mineral of the same composition essentially, from Pressburg, Hungary, has 

 been analyzed by von Hauer. See Wien. Sitzb., xi, 609, 1853, and author's Min., p. 

 295.] 



