MINERAL RESOURCES OF THE STATE OF NEW YORK 65 



classed by mineralogists with the opal varieties of silica. The better 

 grades of diatomaceous earth contain not more than 2 per cent of 

 impurities in the form of iron oxides, alimiina and lime, with 85 per 

 cent or more silica, the rest being water. 



Uses. By reason of its hardness and uniform fineness of grain 

 diatomaceous earth makes a good abrasive. It is extensively 

 employed in polishing powders and scouring materials for metals. 

 According to Frank J. Katz in an article in the Mineral Resources 

 for 191 5, its uses have been considerably extended of late, so that 

 the demand for it has steadily grown. Among the different func- 

 tions which it serves are as a filtering agent, as an insulator for 

 steam pipes, boilers and in fireproofing, as an ingredient of phono- 

 graphic records, as an absorbent in artificial fertilizers and as a base 

 for the manufacture of water glass. It has been employed also in 

 the production of cements, glazes, artificial stone, paints and pig- 

 ments, fireworks, matches and various other commodities. 



Occurrence. The principal deposits of diatomaceous earth are 

 found in the Adirondack lakes. Most is known of the deposits in 

 Herkimer county, which have been reported upon by Charles F. 

 Cox, as noted in the appended list of references. One of the local- 

 ities. White Lead lake, in southern Herkimer county has been 

 known for many years and has been the source of considerable 

 quantities of the material for commercial use. The deposit in that 

 lake is said to cover an area of about 4 acres and to have a thickness 

 of from 2 to 30 feet. It lies below 4 feet of water. The material 

 after excavation is purified by washing and settling in vats, then 

 compressed and dried. The Adirondack Diatomaceous Earth Co. 

 has worked the deposit in recent years. An analysis by Dr Gideon 

 E. Moore, as reported by F. J. H. Merrill showed the following 

 composition. 



SiOj 86.515 



A1203 



.449 



FeaOs 



.374 



CaO 



.120 



H2O and Volatile 



12.120 



Undetermined 



.422 





100.000 



Construction work on the Mohawk & Malone Railroad about the 

 year 1892 brought to notice several occurrences in northern Herkimer 

 county. The localities for diatomaceous earth in that section 

 include Clear lake. Big Crooked lake, Hawk lake, Chub lake, Roilly 

 pond and one or two unnamed ponds, which altogether hold an 

 immense quantity of the material. The deposit in sight in White 



