1896.] Mineralogy and Crystallography. 933 
hedral symmetry. The forms developed on some crystals from Monte 
Poni had suggested trapezohedral hemihedrism in the tetragonal sys- 
tem. 
Wulfenite from several localities has been reported to be hemimor- 
phic, on the strength of the polar development of the crystal form, but 
neither the etched figures nor the pyroelectric behavior of the crystals 
bears this out. Both wulfenite and scheelite act alike in these latter 
respects and appear to be pyramidal hemihedral, without difference in 
the two directions of the vertical axis. 
Chalcolite, disthene, tourmaline, vesuvianite, dioptase, willemite, 
nepheline, beryl, adularia and some of the triclinic feldspars were also 
etched, with the result of confirming the higher symmetry in each 
case where doubt could exist. Nepheline, as already established by 
Baumhauer, belongs to the pyramidal hexagonal class of Groth (1st 
hemimorphic tetartohedral division of the hexagonal system, Liebisch). 
ey mene Mangano-columbite and Microlite from Rum- 
ord, Maine.—These minerals were discovered in pegmatite associa- 
ted with shake, feldspar, muscovite, tourmaline, lepidolite, spodumene, 
amblygonite, beryl, cassiterite and columbite. They are described by 
. W. Foote.’ The pollucite, though rare, occurs in rather large 
masses difficultly distinguishable from white quartz. The analysis 
proves the mineral to be chemically identical with that from Hebron, 
Maine, and seems to sustain the view of Wells that the formula is 
H,Cs, Al,(SiO,),. 
The Mangano-tantalite is in the torm of dark reddish-brown crys- 
tals resembling rutile. A qualitative analysis revealed the presence of 
Mn, Ta and Ni. The specific gravity, 6.44, would indicate that the 
last two elements are present in about equal proportions. The form 
differs somewhat from columbite, as shown among other facts adduced, 
by the axial ratios. 
Columbite. Mangano-columbite. 
ye 8285 : 1 :.8898 8359 : 1: .8817 
Microlite in beautiful honey-yellow crystals 2 mm. in diameter have 
a specific gravity of 5.17.. The prevailing form is the octahedron, ` 
modified by the dodecahedron and sometimes by (113). 
Epidote and its Optical Properties.—The peculiar appearance 
of a gray epidote from Huntington, Mass., led to its detailed investiga- 
tion by Forbes.‘ The light color is evidently due to the low percent- 
3 Am. Jour. Sci., CLI, pp. 457-461, June, 1896. 
t Am. Jour. Sci., CLI, pp. 26--30, 1 
