1894.] Mineralogy and Petrography. 425 
France, are reported by Gonnard”, and some fine crystals of pinite™ 
from Issertaux, near St. Pardoux in the Auvergne. 
Miscellaneous.—In his development of the theory of the consti- 
tution of the micas, Clarke” has reached the problem of the lithium 
members of the group. This he solves by supposing lepidolite to be an 
admixture of the simple molecules Al F, Si, O, R,’, in which R is 
principally lithium, and Al, (SiO), R,’, in which R; may be either 
K,H or KH,. 
Retgers”® suggests molten phosphorus and a solution of phosphorus 
in CS, as media for use in determining the indices of refraction in 
highly refracting substances. A tiny fragment of the phosphorus may 
be melted between two object-glasses, when it spreads as a thin sheet 
between them, and, upon cooling, remains transparent. Its refractive 
index is 2.144. That of a saturated solution of the substance in CS, is 
1.95. 
Some time ago, Damour” suggested the name chloromelanite for one 
of the varieties of jade found in ancient implements. He discovers now 
that the material contains garnets and pyroxene. It thus resembles 
the rock eclogite. The pyroxene from a Mexican specimen is composed 
as follows : 
SiO, AlO, FeO, CaO MgO NaO Total Sp. Gr. 
56.57 1721 886 444 212 10.70— 99.90 3.37 
Nordenskjéld” has begun the study of snow crystals. The first con- 
tribution to his discussion is a series of handsome photographs of 
a large variety of flakes, including prismatic, stellar and other forms 
some of which contained liquid enclosures at the time of their fall. 
z Ib., XVI, p- 10. 
*Ib., XVI, p. 16. 
” Bull. Am. Chem. Soc., XV, May, 1893. 
* Neues Jahrb. f. Min., etc., 1893, II, p. 130. 
“Bull. Soc. Franc. Min., XVI, p.57. Cf. also foot-note No. 14. 
Ib; AVL p- 59. 
