CALCAREOUS SPAR. 117 



called statuary marble. The best is as clear and fine grained 

 as loaf sugar, which it much resembles. 



Compact limestone. — The common secondary limestones, 

 breaking with a smooth surface, without any appearance of 

 grains. The rock is very variously colored, sometimes of 

 a uniform tint, and frequently in bands, blotches or veinings, 

 and always nearly dull until polished. The varieties form 

 marbles of as many kinds. 



r^tmlcstone, Anthraconite. — A limestone, either columnar 

 >r compact, which gives out a fetid odor when struck.. /\ 



Plumbocalcite, from Cornwall, contains 2^34 per- cent, qf 

 :arbonate of lead. 



Dif. The varieties of this species are easily distinguished 



!>y their being scratched easily with a knife, in connection 



(tvith their strongly effervescing with acids, and their com. 



fplete infusibility. Calc spar is not so hard as aragonite, 



and differs entirely in its cleavage. 



Obs. Crystallized calcareous spar occurs in magnificent 

 forms in the vicinity of Rossie, New York. One crystal 

 from there now at New Haven weighs 165 pounds. Some 

 rose and purple varieties from this region are very beautiful. 

 Splendid geodes of the dog-tooth spar variety occur in lime- 

 stone at Lockport, along with gypsum and pearl spar. Ley- 

 den and Lowville, N. Y., are other localities. Bergen Hill, 

 N. J., affords beautiful wine-yellow crystals in amygdaloid. 

 Argentine occurs near Williamsburg and Southampton, Mass. 

 Rock milk covers the sides of a cave at Watertown, N-. Y., 

 and is now forming. ( Stalactites of great beauty occur"*Tn 

 Weir's and other caves in Virginia and the Western States ; 

 also in Ball's cave at Scoharie, N. Y. Chalk occurs in 

 England and Europe, but has not been met with in the Uni- 

 ted States. Granular limestones are common in the Eastern 

 and Atlantic States, and compact limestones in the middle 

 and Western, and some beds of the former afford excellent 

 marble for building and some of good quality for statuary. 



Uses. Any of the varieties of this mineral when burnt, 

 form quicklime. Heat drives off the carbonic acid and leaves j 

 the lime in a pure or caustic state. Some limestones con- ; 

 .ain a portion of clay disseminated throughout it, and these \ 

 burn often to hydraulic lime, a kind of lime, of which a ' 



'What is said of compact limestone'? Hew is this species distill- 

 jpushed from other species'? What are the ises of limestone 



