Geology and Mineralogy. 417 



Barkevikite is a hornblende mineral near arfvedsonite, but dis- 

 tinct from that in optical characters. Calciothorite is a hydrous 

 mineral consisting of thorium and calcium silicate and probably 

 (like thorite, orangite, eucrasite, frejalite) an alteration product 

 of an original thorium silicate near zircon in form and composi- 

 tion (ThSiOj. 



Melanocerite is a complex silicate of the cerium metals, yttrium 

 and calcium, with other substances in small amount including 

 3*19 p. c. B 2 3 ; it is found in tabular rhombohedral crystals of a 

 dark brown color. Nordenskioldine is a mineral having the re- 

 markable composition CaO . SnO„ . B 2 3 . It occurs in tabular 

 crystals belonging to the rhombohedral system. Color sulphur 

 yellow. Hardness = 5 - 5-6 ; sp. gravity = 4-20. Rosenbuschite 

 is a silicate of calcium and sodium with zirconium, titanium and 

 also lanthanum in small amount. It occurs in orange-gray mono- 

 clinic crystals near wollastonite and pectolite in angle, and is 

 characterized as a zirconium-pectolite. Hardness = 5-6 ; sp. 

 gravity, 3*30. — W. C. Brogger in Geol. For. Fork., vol. ix, 

 247, 1887. 



Barysil. — A new lead silicate from the Harstig mine, Pajs- 

 berg, Sweden. It occurs in iron ore with calcite, yellow garnet, 

 tephroite and galena. Crystallization hexagonal with basal cleav- 

 age. Color white. Hardness = 3 ; sp. gravity, 6*1 1-6 '55. Anal- 

 ysis gave : 



Si0 2 PbO MnO FeO CaO MgO ign. 



16-98 77-84 3-49 046 0-41 0-58 0-66 = 100-12 



This corresponds to 3PbO . 2Si0 2 . — A. Sjogren and Lundstrom 

 in (Efv. Vet.-Akad. Fork., xlv, 7, 1888. 



Belokesite (Belonesia), Cryphiolite (Crifiolite). — Two species 

 described by A. Scacchi in a memoir upon a fragment of an old 

 volcanic rock enveloped in the Vesuvian lava of 1872. Belone- 

 site occurs in minute acicular crystals referred to the tetragonal 

 system ; they are white and transparent. Qualitative tests lead 

 to the conclusion that in composition it is a molybdate of magne- 

 sium, MgO . Mo0 3 . 



Cryphiolite occurs in small tabular monoclinic crystals covered 

 and concealed (as the name suggests) by apatite. The color is 

 honey-yellow; sp. gravity = 2-674. An analysis gave : 



P 2 5 48-91 MgO 33-58 CaO 1460 Loss 2"91 = 100 



The presence of fluorine is suggested and the possible amount 

 estimated as 6*93 p. c, which brings the mineral near wagnerite 

 in composition. — Mem. Accad. JSTapoli, II, i, No. 5. 



Bementite. — Occurs in stellate aggregations with foliated 

 structure, resembling pyrophyllite. Friable. Sp. gravity, 2-981. 

 Color pale grayish yellow. An analysis yielded : 



Si0 2 MnO FeO ZnO MgO H 2 



3900 42-12 [3-75] 2-86 3-83 8'44 = 100 



This corresponds approximately to 2(H„,Mn)0 . Si0 2 ; the water 

 goes off above 200°. Occurs embedded in calcite at Franklin 



