1894.] Mineralogy. ` 873 
SiO,. This compound should have either orthorhombic or monoclinic 
symmetry, with £ equal to 90° and an axial ratio a: b: c=1.086: 1: 
1.887. i 
Leucite from New Jersey.—Kemp* argues for the presence of 
partially decomposed leucites in a dyke rock at Rudeville, Sussex Co., 
N. J., from a micro-chemical test indicating the presence of potassium, 
and from remains of leucite twinning, in spheroids now largely made 
up of analcite, calcite, feldspar, and other supposed secondary pro- 
ducts. 
Variscite from Utah.—Packard?® gives an analysis of a specimen 
of compact or cryptocrystalline variscite from a quartz vein near Lew- 
iston, Utah. The analysis is as follows: 
H,O 22.95 P,O, 4440 . ALO,(By difference) 32.65. 
Utilization of Auerbach Calcite for Nicols.—An attempt 
has been made" to utilize the clear calcite from Auerbach on the 
Bergstrasse, Germany, for Nicol's prisms. Four ordinary Nicols with 
inclined end faces were prepared by Schmidt & Haensch of Berlin, 
and although these are equal to the medium quality Nicols prepared 
from Iceland spar in the matter of extinction, they nevertheless con- 
tain inclusions, air bubbles, etc., which are visible even to the naked 
eye. Dr. Hoffman, the owner of the Auerbach quarries, still hopes to 
secure material pure enough to take the place of Iceland spar. The 
material already tested will suffice for technical purposes. 
Crystallization of Willemite.—Willemite has been supposed to 
have rhombohedral tetartohedral symmetry from the similarity of its 
rhombohedral angles to those of phenacite. Penfield” studies crystals 
from the Merritt Mine, N. M., Sedalia Mine, Salida, Col., and Frank- 
lin, N. J. In the specimens from the first and last mentioned locali- 
ties, rhombohedrons of the second and third orders were observed and 
measured, showing that the system is what has been supposed. On 
the crystals from the Merritt Mine the second and third order rhombo- 
hedrong are# P 2! and $ P$! respectively. One of the types from the 
4 a1 
Franklin Mines is terminated by a third order rhombohedron 3717 
alone, thus resembling the phenacite crystals from Mte. Antero, Col. 
*Am. Jour. Sci., (3) xlvii, pp. 339-340. 
*Am. Jour. Sci., (3) xlvii, pp. 297-298. 
Zeitschrift für Instrumentenkunde, 14te Jahrgang (1894), p. 54. 
Am. Jour, Sci., (3), xlvii, pp. 305-309. 
