26 NEW YORK STATE MUSEUM 



APATITE 



The common carrier of phosphorus in rocks and ores is the 

 mineral apatite which is essentially calciiim phosphate, although 

 it contains also small amounts of the fluoride and chloride of cal- 

 ciimi. Apatite is the source of phosphorus in iron ores, its pro- 

 portions determining largely the quality of the iron that may be 

 made from particular ores; and is widespread in many rocks, 

 especially of the igneous class, but rarely constitutes more than 

 one per cent of the mass. Though a very common mineral, there 

 are few deposits of apatite which would repay the costs of mining 

 for itself alone. The abundant rock phosphates, which resemble 

 apatite somewhat in composition, serve most requirements quite 

 as well and are obtainable at a low cost. 



Apatite and phosphate materials generally are sold on the basis 

 of chemical analysis. Rock phosphate ordinarily carries from 60 

 to 70 per cent of the tri-calcium phosphate or bone phosphate, 

 whereas apatite in pure state contains 90 per cent. If an apatite 

 concentrate were obtainable with an average of 75 or 80 pfer cent 

 of bone phosphate it would have a certain preference in the market 

 by reason of the scarcity of materials of that grade which are 

 serviceable for the manufacture of metallic phosphorus and chemical 

 preparations. 



The production of apatite is carried on at present in one locality 

 as a by-product of the mining and milling of iron ores. This is 

 Mineville, Essex county, where Witherbee, Sherman & Co. have for 

 years been engaged in the production of an apatitic magnetite that 

 occurs in the so-called Old Bed group of deposits. The ore as 

 mined carries as much as 8 or 10 per cent of the phosphate mineral 

 in the form of small grains or crystals intermixed with the particles 

 of magnetite. By crushing the apatite is mostly released from 

 mechanical combination and can then be separated readily by the 

 usual magnetic methods employed for concentrating lean magnetites. 

 Although the magnetite in this instance is sufficiently high in iron 

 content to be used in lump form, its treatment is desirable for most 

 furnace uses. As a result of the separating process a tailing is 

 made which contains most of the apatite originally present in the 

 ore, a small percentage of magnetite and considerable amount of 

 quartz, hornblende and feldspar which are constituents of the 

 gneissic country rock. Large quantities of these tailings have 

 resulted from milling of the Old Bed ores. In order to put them 

 in form for commercial use they require further treatment. They 

 are reground and reconcentrated in magnetic machines, wet tables 



