VARIETIES Ot' LIMESTONE. A number of names have been given to different varieties of lime stone. of which the more important are the fol lowing: Crinoidal liniestonc, a variety contain ing fragments of crinoid stems. Coquina ly.v.1. a variety composed of loosely eemented shell fragments. Chalk (q.v.), a white variety of limestone formed chiefly of foraminihral shells. Do/owite (q.v.l, a limestone containing both car bonate of lime and magnesia. Hydraulic lime stone, an aluminum, variety having the property of hardening under water after it has been burned. Marl (q.v.). a soft. calcareous mud. formed in the bottom of many ponds. Marble (q.v.), strictly speaking. is a crystalline limestone, but the term has been expanded in commercial vise to include any limestone that will take a polish. (q.v.), a limestone composed of small spherical grains. Sarcharoidal limestone, a coarsely granular variety. r line and tufa, calcareous deposits formed around the mouths of springs.
Uscs. The chief use of limestone is for build ing purposes, for which it is found Valuable on account of its wide distribution. dense structure, and massive character. 'Marble is used for decorative work. Limestone is also widely used as a road material and in the manu facture of lime (q.v.). \\ lien mixed with clay or shale in certain proportions and burned :tad ground it forms Portland cement. Many argil
laceous limestones when burned also show by draulie properties, and such are put on the mar ket under the name of or natural rock cement. Other uses of limestone are as a flux in iron and lead smelting. and in glass manufac ture. When burned to Hine it is employed for making mortar and chloride of lime: and is used in gas. soap. and sugar manufacture. as a disin fectant. for bleaching. in the manufacture of Bessemer steel, etc. The total value of the lime stone produced in the United states in 1901 was $2(1.-1013.S97. Of this amount repre sented the value of stone sold f, r lime for blast furnace flux.
BthuoGnAertv. Burnham, History and of and Marbles I Boston. I ) : I op kin-. "Marbles and Other .Irkonso.: Ocological Sum y port, N'ol. iv. I Little Pool:. : Lane. Limestones and Their Uses," Engineering and 11 inina Journal I New Y oil:. 19001 : Lies, 'Limestone Quarries of Eastern New York. Western Vermont. setts. and Connecticut." United Sloh., (froloaical y Report : Ilivs. "Thi.
Limestones of New and Their Economic Value." Annual Pr port of this ir loll,. Oeologist ( Albany. I !MO . See um "zToN : MAnnu:: CEMENT: LIME; MARL.