Mineralogy and Petrography. 1023 
itself.— Beryllonite. Ina preliminary note Prof. E. S. Dana! sug 
a 
in Polk county, N. C., and at Pilot Mountain, Burke county, in 
the same State. It crystallizes in the orthorhombic system like 
brookite, but its axial ratio, as calculated by Des Cloizeaux, is 
99275 : 1 : 92337. The color of the mineral is yellow or brown, 
art hardness about 6, specific gravity 4.285, and streak yellowish 
white. 
Rare Minerars.—Bertrandite. Heretofore this mineral has been 
found only in small crystals at various localities in Europe, and itserys- 
tallographic characteristics have not been thoroughly investigated. 
A new find at Mt. Antero, Colorado, affords Mr. Penfield‘ a crys- 
tal of sufficient size to admit of exact measurements of the crystal- 
lographic constants. According to Mr. Penfield, the mineral is 
orthorhombic with a: b : c = .5723: 1: .5953, and 2H = 101° 10’ 
for yellow light. The hemimorphic development of the basal plane 
cannot be explained. The crystals are attached to ques and are 
associated with phenacite, orthoclase, muscovite and fluorite. They 
have a hardness of 6-7, a specific gravity of 2.598, and consist of :— 
SiO, BeO CaO H:O 
51.8 39.6 1.0 8.4 
Piedmontite. The optical properties of the manganese epidote pied- 
montite have recently been very carefully studied by Dr. Kot6,’ of 
Japan, who finds it quite wide spread as a constituent of Japanese 
rocks, In a piedmontite-schist consisting of quartz, piedmontite, 
muscovite, garnet, rutile, feldspar, ete., the piedmontite is well crys- 
tallized with oP, œ Pj, 4 Pa, P, and Px predominating. The 
mineral has an extinction of 3°, and is pleochrois as follows: vr = 
deep reddish violet; t = brownish red; pi = light violet. The 
absorption is vr > t > pi, whereas in common epidote it is t > pi 
vr. An analysis yielded :— 
SiO, AlO, FeO, Mn,O, CaO MgO K,O NaO H,O 
16 2252 9.88 643 2206 | 4 3.20 
), 169. 
* Amer. Jour. Sci., 1888, Oct., p. 272. 
* Ib., July, p. 52. 
Quart. Jour. Geol. Soc., Aug., 1887, p. 474. 
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