C A L 



[65] 



C A L 



2. A mineral variety of hornblende, 

 called also Actynolite, or Actinolite. 

 See Actinolite. 



CALC-SINTEB. Stalactitical or stalag- 

 mitical carbonate of lime. This is 

 so called from the German kalks, 

 lime, and sintern, to drop. It is 

 deposited from thermal springs, 

 holding carbonate of lime in solu- 

 tion. 



CALCAI'BE GEO'SSIEE. (Fr.) A coarse 

 limestone, often passing into sand, 

 and abounding in marine shells ; it 

 contains by far the greater number 

 of the fossil shells which character- 

 ize the Paris basin. Kot fewer 

 than four hundred distinct species 

 have been found in a single locality 

 near Grignon. Dr. Berger observes 

 that this variety of limestone was 

 thought to be very scarce in 

 England, but that he is disposed to 

 believe, upon a further examination, 

 it will be found to occupy a great 

 extent of country. To M. Brong- 

 niart we are indebted for much 

 valuable information concerning 

 the calcaire grossier. The mean 

 specific gravity of specimens of the 

 calcaire grossier from different 

 parts of England, Dr. Berger gives 

 as 2-579, ranging from 2-466 to 

 2 '666. The calcaire grossier cor- 

 responds with our Bembridge series. 



CALCAI'EE MOELLON. The name given 

 by M. Marcel de Serres to certain 

 marine beds of limestone found in 

 the south of France and comprised 

 in the supracretaceous group. The 

 calcaire moellon is commonly work- 

 ed as a building stone in the south 

 of France. 



CALCAI'EE siLfcEUX. (Fr.) A com- 

 pact silicious limestone, occupying, 

 according to the early opinion of 

 Brongniart, the place of the calcaire 

 grossier where that is wanting, 

 who discovered in it the silicate of 

 magnesia. Like the calcaire gros- 

 sier, the calcaire siliceux belongs 

 to the eocene tertiary period ; it 

 has been found in the Paris basin, 



in the Isle of Wight, and in 

 several parts of France. 



CALCA'BEOTJS BOCX. Limestone. 



CALCA'BEOUS SPAR. Crystallized car- 

 bonate of lime. Calcareous spar 

 occurs crystallized in a vast variety 

 of forms, but its primitive form is 

 invariably a rhomboid with obtuse 

 angles of 1055', and 7455', the 

 crystals break easily with the 

 stroke of a hammer. It consists of 

 nearly 57 parts of lime and 43 

 parts and a fraction of carbonic 

 acid. The finest specimens are 

 brought from Derbyshire, but it is 

 found in almost all parts of the 

 globe. Calcareous spar is often as 

 transparent as rock-crystal, but it 

 is usually coloured of various tints 

 by the presence of oxide of iron. 

 All its forms, which amount to 

 nearly 500, are derived from the 

 rhomb. When in irregular forms, 

 it may always be distinguished 

 from quartz by its admitting of 

 being scratched with a knife, and 

 by its effervescing when weak 

 nitrous acid is applied to it. Ice- 

 land spar is this mineral in its 

 purest form, and affords the readiest 

 means of observing the optical 

 phenomenon of double refraction. 

 Its almost universal diffusion is 

 probably owing to its partial solu- 

 bility in water ; in this condition 

 it niters through the crevices 

 abounding in all strata, and re- 

 crystallizes as the water evaporates. 

 When this filtration continues so 

 uninteruptedly as to prevent by its 

 mechanical action crystallization 

 from taking place, and yet so 

 gradually as to admit of the solid 

 mineral being deposited from the 

 water, those curious and beautiful 

 concretions called stalactites are 

 produced, which ornament, in so 

 singular a manner, most caverns in 

 rocks or mountains formed princi- 

 pally of limestone. 



CALCA'BEOUS TTJPA. Beds of calca- 

 reous tufa are sometimes formed in 



