340 T. S. Hunt on some American Minerals. 
Art. XX XIIL—#ramination of some American Minerals; by 
T. S. Hunt, of the Geological Commission of Canada. 
Columbite.—T ue specimen here described is from a locality at 
Haddam, Connecticut, in which the mineral was recognized by 
myself, while visiting the place, six years’since. It occurs some 
two miles from the famous locality of chrysoberyl, where also 
columbite.is met with in minute crystals, and is in a huge granitic 
vein traversing gneiss. The vein is made up of large cleavable 
forms of yellowish-white feldspar and brown muscovite, with 
quartz and beryl. ‘The latter mineral is sometimes found in 
erystals four or five inches in diameter, and a foot or two in 
length; these are subtranslucent and brownish or greenish-yel- 
would constitute gems. They are frequently modified by trunca- 
rounded, and do not admit of accurate admeasurement. 
columbite occurs disseminated through the vein, alike in the feld- 
spar, mica and beryl; some of the crystals were said to have. 
been several ounces in weight, and had been carried off by ame- 
teur collectors as specular iron ; a crystal since procured from the 
locality by Prof. Silliman, Jr., weighs 36 ounces. The smaller 
crystals were abundant and often beantifully perfect, some of them 
are imbedded in translucent yellow beryl, and have the form rep- 
resented in figure 1, p. 401 of Dana’s Mineralogy, 3d edition. — 
The hardness of the columbite was about 6, and the specific 
a little lime, which was precipitated as oxalate. The fo lowing 
results were obtained : = 
Metallic acid, 3 ‘ : 80°60 
Protoxyd of iron, : ‘ — wee 
2 of manganese, . j 3°25 
Lime, . , ; ; a -50 
Oxyd of tin, ‘ : F a trace 
