612 THE AMERICAN NATURALIST. (VOL. XXXII. 
recent finds of better material have first made a complete description 
possible. But few specimens in all have yet been found, all coming 
from the Trotter mine, at a supposed depth of about one thousand 
feet. It is associated with willemite, massive brown garnet, phlogo- 
pite, axinite in small crystals, datolite, and a reddish-brown mineral 
occurring in slender prismatic crystals, whose investigation is not 
yet complete, but which proves to be a new silicate containing lead, 
iron, and calcium as essential constituents. 
The name of the new mineral, clinohedrite, is suggested by the 
prevalence of forms having no parallel faces. It is monoclinic in crys- 
tallization, and of special interest as belonging to the hemihedral divi- 
sion of that system, the “domatische klasse” of Groth, hitherto 
represented among mineral substances only by occasional crystals of 
pyroxene, which, however, seems to be normally holohedral. The 
crystals were well suited to measurement, upwards of 4 mm. in great- 
est dimension, and of two types. 
The axial ratio is as follows: a:b: c = 0.6826: 1: 0.3226, B =76°4’. 
Forms observed: ; 
b, oro n, 120 P, III $331 O, 131 
h, 320 l, 130 Px III S, 551 Ox, 131 
m, IIo e, IOI q, fii 177 x, 131 
my, TIO èy ioi qy IIT u, 531 y, 121 
Cleavage perfect parallel to b, oro, hardness 5.5, specific gravity 
3:33: 
Many crystals are transparent, the color varying from amethys- 
tine to colorless or white. Double refraction negative and not very 
strong. Plane of optic axes at right angles to oro; the crystallo- 
graphic axis b, the acute bisectrix. Exhibits distinctly the phenom- 
ena of pyro-electricity, the faces p, e and upper extremities of m 
becoming, on cooling, positively electrified, the diagonally opposite 
faces, x, y, p, e, negatively. Chemical composition : 
SiO, ZnO MnO CaO MgO H,O (Fe.Al)203 Sum 
27.22 37.44 0.50 26.25 0.07 8.53 0.28 100.32 
corresponding to the formula H-Zn Ca SiO; or (ZnOH) (CaOH) SiO;, 
analogous to that of calamine (ZnOH), SiO}. 
Pyrognostics : in closed tube, unchanged at low heat, at faint red- 
ness exfoliates, whitens, and gives off water. Fuses at 4 toa yellow- 
ish enamel. Soluble with gelatinization in HCl. 
