Reéxamination of American Minerals. 251 
61. Brown Hematite. 
This ore occurs in concretionary masses of a dark liver color, 
and compact structure, associated with nearly all the minerals of 
this mine—it very commonly forms a lining to cavities in galena, 
in which are found crystals of anglesite and cerusite ; sometimes 
it lines cavities in the rock that are completely filled with cubical 
alena. Acicular concretions of the hematite are found travers- 
ing crystals of anglesite and cerusite. A specimen of the purest 
hematite gave for its composition 
Peroxyd of iron, - - . - - 80°32 
Oxyd of copper, - - - - ° - "94 
Oxyd of lead, : - - - - 151 
a : ; ‘ : . - 14°02 
Silica, ; : : : ‘ a: 
100-21 
62. Fluor Spar. 
The remarkable feature of the fluor spar of this mine is the ab- 
sence of color; all the specimens yet found being colorless and 
transparent. ‘The crystals are very perfect and beautiful, yet 
small; it is sometimes in globular concretions, of crystalline 
structure radiating from the centre. he cube, which is the more 
common crystalline form, is sometimes very much modified by 
the truncation of the edges and angles. A specimen that was ex- 
amined gave a sp; grav. of 3°15, and the following composition : 
Fluorine, - . 48°29 
Calciu - - - - - - - 5081 
Phosphate of lime, = - - - - - a trace 
It is associated with cale spar, and in some instances in a 
remarkable manner, mentioned under the head of calc spar. 
Galena and blende are interspersed through it. Its occurrence in 
the mine was first noticed at the depth of three hundred feet, 
and since then it has been found abundantly. , 
63. Cale Spar. » 
There are a variety of interesting forms and associations of 
this mineral. The two most common are the dog-tooth spar an 
the hexagonal prism with a three-sided summit, and occasionally 
the hexagonal prism with flattened its lik gonite. Some- 
times slabs of this mineral are found, with a surface of eight or 
shape throughout the entire length ; again, these slender forms 
