COMPOUNDS OF CALCIUM. 213 
mammillary with a compact fibrous structure. 
Small crystals are occasionally transparent 
and colorless, but the usual color is green, 
often yellowish green, bluish green, and oray- 
ish green ; sometimes Sra blue, reddish 
or brownish. Coarse crystals nearly ee 
Lustre vitreous to subresinous. Te 
=$-3:25. Brittle. Some varieties a culie: 
resce when heated, and some become electric 
by friction. 
Composition. Ca, Os P.+% (Ch, F.) = if without fluorine 
Phosphorus pentoxide 40°92, lime 53°80, chlorine 6°82=100. 
When chlorine is present in place of fluorine it is called 
c lor-apatite, and when the reverse, flwor-apatite. B.B. in- 
fusible except on the edges. Dissolves slowly in nitric acid 
without effervescence. Its constituents are contained in 
the bones and ligaments of animals, and the mineral has 
probably been derived i in many cases from animal fossils.* 
Massive apatite is often called Phosphorite ; and the pale 
yellowish-green crystals, Asparagus stone. ‘Osteolite is a 
white earthy apatite. Hupyrchroite is a fibrous mammil- 
lary variety from Crown Point, Essex County, N. Y. 
Fossil excrements, called coprolites, occur in stratified 
rocks, and sometimes constitute extended beds ; and they 
consist chiefly of calcium phosphate. Gwano contains more 
or less calcium phosphate along with hydrous phosphates 
and some impurities. 
Diff. Distinguished from beryl by its inferior hardness, 
it being easily scratched with a knife ; from calcite by dis- 
solving in acids without effervescence ; from pyromorphite 
by its difficult fusibility, and giving no metallic reaction 
before the blowpipe. Phosphoric acid may be detected by 
moistening it with sulphuric acid and igniting it B.B., 
when it imparts a dirty green color to the flame. 
Obs. Apatite occurs in gneiss, mica schist, hornblende 
schist, granular lLmestone. In microscopic crystals it is 
sparingly present in almost all crystalline rocks, the ig- 
neous as well as metamorphic. The best crystals in the 
United States occur in granular limestone ; “the crystals 
from the limestone of St. Lawrence County, Noi. Soare 




* Bones contain 25 per cent. of calcium phosphate, with some fluoride of calcium, 3 
to 12 per cent. of calcium carbonate, some magnesium phosphate and sudium chloride, 
besides 33 per cent. of animal matter. 
