COMPOUNDS OF CALCIUM. ay 
earbonaccous material of organic origin, and is proved by 
the limestones becoming white when burnt. 
Stinkstone, Anthraconite. A limestone which gives out 
a fetid odor when struck. This odor is caused by certain 
bituminous materials present in the rock. 
Lithographic stone. A very compact fine-grained lme- 
stone of a gray or grayish-yellow color. 
Hydraulic limestone. An impure limestone. It contains 
silica and alumina in such a condition that, when burned, it 
will make a cement that hardens under water. 
Diff. Distinguished by being scratched easily with a knife, 
in connection with strongly effervescing in dilute acid, 
and its complete infusibility. Calcite is not so hard as 
aragonite, and possesses a very distinct cleavage, which 
aragonite does not. | 
Obs. Crystallized cale spar occurs in magnificent forms 
in the vicinity of Rossic, New York. One crystal from 
there, now in the Peabody Muscum at New Haven, weighs 
165 pounds. Some rose and purple varieties from this 
region are very beautiful. Large geodes of the dog-tooth 
spar variety occur in limestone at Lockport, ‘along with 
gypsum and pearl spar. Leyden and Lowville, N. Y,, are 
other localities. Bergen Hill, N. J., affords beautiful 
wine-yellow crystals in amyedaloidal “cavities ; also the 
Lake Superior copper mines. Argentine occurs near 
Williamsburg and Southampton, Mass. Jtock milk covers 
the sides of a cave at Watertown, N. Y., and is now 
forming Séalactites of great beauty occur in Weir’s and 
other caves in Virginia and in the Western States ; also in 
Ball’s Cave at Scoharie, N. Y. Chalk occurs in England 
and Europe, and in Western Kansas in the United States, 
Granular limestones are common in the Eastern and At- 
lantic States, and compact limestones in the Middle and 
Western States, and some beds of the former afford excellent 
marble for WaeuLe and some of good quality for stat- - 
lary. 
Any of the sitios of this mineral when burnt form 
quickline, heat driving off the carbonic acid and leaving 
the lime in a caustic state. In this state it is used for mak- 
ing mortar by mixing with water and sand; a calcium 
hydrate resulis which becomes slowly carbonated through 
carbonic acid in the atmosphere, See further the chapter 
on Rocks, for the uses of limestone. 
