108 
[Assembly 
mineral. From the filtered liquor, after the addition of water, the oxide 
of iron was thrown down by ammonia. The following are the results, 
viz : 
Phosphate of lime, 92 . 85 
Oxide of iron, with a little alumina, 5 . 20 
Silica, (foreign,) 0.50 
Moisture, 1.25 
Fluoric acid, trace. 
The oxide of iron, silica and alumina, are undoubtedly accidental 
ingredients, and the mineral is therefore a phosphate of lime, although 
in a rare form. It was found near Crown Point, in Essex county. 
The presence of fluoric acid in the phosphate of lime, may be shown 
by reducing it to powder, and then mixing sulphuric acid with it, in a 
platinum crucible. Upon covering the crucible with a plate of glass, 
and applying a gentle heat, the glass is soon corroded. In this way I 
have detected the presence of fluoric acid in the crystallized phosphate 
of lime in Orange county, and also in that from Rossie, St. Lawrence 
county. A very slight effect only was produced, when the fibrous va- 
riety was thus operated upon. 
Pyroxenic Steatite. 
This substance was described by Dr. Emmons, in the first report of 
the survey, under the name of Rensselaer it e. His description is as fol- 
lows : 
Hardness, =: 3.5 or 4.0. Specific gravity, 2.874. Form, oblique 
rhombic prism. M on M = 94° and 86° ; P on M r= 106° 30^— 
Cleavage parallel to P. Colour, white, yellowish-white, or dark slate. 
Fracture uneven. Corresponding varieties somewhat granular. Indi- 
viduals strongly coherent. Before the blowpipe, it fuses with difficulty 
into a white enamel ; moistened with nitrate of cobalt, it assumes a pale 
flesh red colour. 
Dr. Emmons furnished me with specimens of the above mineral from 
Canton, in St. Lawrence county, more than a year ago. During the 
last summer, Dr. Horton and myself found it in great abundance near Ox- 
bow, Jefferson county, at Governeur, St. Lawrence county, and else- 
where. 
My examination of this substance was conducted according to the 
usual process for the anal3^sis of minerals not decomposable by acids. 
The following are the results : 
Silica, 59.75 
Magnesia, 32.90 
Lime, 1.10 
Peroxide of iron, 3.40 
Water, 2 . 85 
The composition, therefore, agrees very well with that of steatite. In 
regard to its crystalline character, it is similar to the steatitic pyroxenes 
of Sahla, noticed by Beudant, which contain from 30 to 60 per cent 
of foreign matters, but which still have the form and cleavage of pyrox- 
ene. Rose has anal3^zed three varieties, the composition of one of 
which is as follows : 
