Geology and Mineralogy. 311 



in Greenland. They occur with segirite, arfvedsonite, endialyte, 

 etc., the association being similar to that of Langesund in Nor- 

 way. 



Xeptanite occurs in short prismatic crystals, belonging to the 

 monoclinic system, and shows perfect cleavage parallel to the 

 fundamental prism of 99° 46'. The hardness is between 5 and 6 

 and the specific gravity 3*234. The color is black, but deep red- 

 brown in very slender crystals. An analysis gave : 



Si0 2 TiO„ FeO MdO MgO K 2 Na 2 



51-53 18-13 10-91 4-97 049 4'88 9-26=100-69 



For this the formula proposed is : 



(f Na„ + KJSi.O, + (f Fe + --MnJTiO, 



Epididymites as is suggested in the name, is near the eudidy- 

 mite of Brogger and is regarded as a dimorphous form of the 

 same compound. It is found in orthorhombic crystals prismatic 

 in the direction of the macrodiagonal, and pseudohexagonal in 

 angle, which character is also shown in its twinning. The 

 angles and axial ratio are not far from those of eudidymite, 

 which, however, has been referred to the monoclinic system. 



An anal- 



The composition is 



the same, 



namely : 



HNaBeSi 3 8 . 



ysis gave : 











Si0 2 



BeO 



Na 2 H 2 



Sp. Grav. =2*548 



73-74 



10-56 



12-88 3-73 



100-91 



— Geol I'd?'. Fork., xv, 195, 1893. 



14. Hautefeuillite is a hydrated phosphate of magnesia and 

 lime from the apatite mines of Bamle, Norway, described by L. 

 Michel. It occurs in lamellar masses having a radiated structure 

 and made up of minute monoclinic crystals elongated vertically 

 and flattened parallel to the clinopinacoid. The hardness is 2 # 5, 

 the sp. gravity 2-435 and it is colorless and transparent. The 

 analysis gave: 



P 2 5 MgO CaO H 2 



34-52 25-12 5'71 34'27 = 99'62 



This corresponds to the formula (Mg,Ca) 3 P 2 B + 8H 2 X), which 

 brings it near bobierrite. The name is given in honor of M. 

 Hautefeuille. — Bull. Soc. Minn., xvi, 38, 1893. 



15. Melanostibian is an imperfectly investigated mineral from 

 the manganese mine, Sjogruf van, in Orebro, Sweden ; it is de- 

 scribed by L. J. Igelstrom. It occurs in massive form either 

 with foliated structure forming thin veins, or in microscopic crys- 

 tals for which the tetragonal or orthorhombic system is suggested. 

 The hardness is 4, the color black, and it is opaque with metallic 

 luster. An analysis (assuming the iron and manganese present 

 as protoxides and the antimony as Sb 2 3 ) gave : 



Sb 2 3 FeO MtiO CaO MgO H 2 



37-50 27-30 29-02 1*97 1*03 1'06 = 98'48 



— Zeitschr. f. Kryst., xxi, 246, 1893. 



