MINERALOGY. 



The proportion of manganefe and iron is fometimes much 

 greater, and there are fcveral intermediate varieties, which it 

 is difficult to determine whether they are to be claffed with 

 brown fpar or fparrv iron-ore. Brown fpar occurs in vems 

 along with galena and other ores of lead, m the mines of 

 Cumberland and Nortluimberland. Fibrous b.wn fpar, 

 both maffive and in balls, occurs in veins in Lower Hungary. 

 Columnar brown fpar has a fplendent luftre and a fohated 

 ftruaure, but no diftina cleavage can be obferved in ,t. 

 The fragments are wedge-ftaped. It has been found at 

 Gerfdorf in Saxony, and Guanaxto in Mexico. The name 

 brown fpar was given to this fpec.es becaufe it changes its 

 colour, on expofure to the air, from a light to a dark brown, 

 bordering on black. 



DuTTERMii-K, ^/y-y^/-. See Silver-Ores. 

 Byssolite, a name given by SaufTure to a variety ot 

 afbeftous adinolite, which occurs in minute acicular di- 

 verging cryftals, which are elaftic. See Actinolite. 



Cacholong, (hiarz agate cacholong, Haiiy, is by 

 feme mineralogifts^confidered as a variety of milk-white 

 chalcedony, by others as a kind of common opal. Cacho- 

 lono- is diilinguiflied by its milk-white colour, its refinous 

 lullre, its even frafture, and its want of tranflucency, except 

 at the edges. It fometimes adheres when applied to the 

 tongue. This mineral accompanies flints and chalcedony, 

 and, according to Brongniart, even pitch-done is fometimes 

 coated with it ; hence it is fuppofed to be the refult of alter- 

 ation in thefe minerals, produced by an unknown caufe, as 

 it is obferved paffing into them by almoil imperceptible 

 gradations. The true cacholongs, which have given the 

 name to this variety, are found near the banks of the river 

 Cach, in Bucharia ; they are fpread over the fields, but are 

 rot rounded ; on the contrary, they form tables compofed 

 of alternate layers of cacholong and chalcedony. Cacho- 

 longs are fometimes cut and employed in jewellery. 

 Calamine. See Zinc-Ores. 



Calcareous Spar, . cryftallized carbonate of lime. 

 See Lime-stone. 



Calc Sinter. See Stalact'ical Jibrous Lime-Jlone, in the 

 article Lime-stoke. 



Calc Ttifa, or Tufaceous Llme-Jlone, a light porous llme- 

 ftone, formed by the dcpofition of calcareous matter, in 

 calcareous fprings, or near lakes or rivers. It frequently 

 enclofes the remains of animals or vegetables which have 

 been encafed and imbedded in it by fucceffive depofitions. 

 See Tufa. 



Calp, a name given by Kirwan to a dark ferruginous lime- 

 ftone, agreeing in many of its charadters with the Englifli 

 lias. See Lias, Addenda. 



Candle Coal. Bituminous coal, fo called on account 

 of the great light which it affords in burning. See Coal. 

 Cat's-E\ e, Ouarz agathe chatoyant, Haiiy ; by fome 

 mineraiogiils caWed falfe opnh It appears to be a variety of 

 agate occurring like the latter mineral in trap rocks, but re- 

 markable for reflefting a peculiar play of colour, refembling 

 that of the eye of a cat, whence its name ; it is ufed in jew- 

 ellery, and is generally cut into ring Hones. Cat's-eye 

 occurs maffive and in loofe angular and rounded pieces ; its 

 colours are various, inclining moll frequently to yellowiffi 

 and greeni(h-grey, and fometimes to brown-red and greyifh- 

 black. It exhibits a beautiful opalefcence when cut in a 

 fpherical form, which proceeds from the fibrous ftrufture, 

 and fometimes from the intermixture of amianthus. It is 

 tranflucent in different degrees ; it has a ffiining vitreo-refm- 

 ous luftre, a fmall conchoidal frafture ; it fcratches quartz. 

 Cat's-eye becomes opaque and fpotted by expofure to the 



blow-pipe. Its fpecific gravity is 2.64. 

 Klaproth, its conftituent parts are, 



Silex - . - - - 



Alumine .... 



Lime ..... 



Oxyd of iron ... 



According to 



95.00 



1-75 

 1.50 

 0.25 



98.50 



Cat's-eye occurs in the Hartz, in Hanover, in trap, witli 

 amianthus, afbeftus, axinite, and calcareous fpar. It is 

 brought from Ceylon, Malabar, Sumatra, Perfia, and 

 Arabia. 



Celestine, fulphate of ftrontian. See Strontian. 



Cerium, or Cerite, Cerium oxyde Jilinfere, Haiiy, an ore 

 of the newly-difcovered metal cerium. (See Cerium.) 

 The colour is between rofe-red and flefh-red, and alfo 

 reddifh-brown ; when pulverifcd it is grey ; it occurs both 

 maffive and diffeminated. The frafture is fplintery, the 

 lullre glimmering and refinous. Opaque (Jamefon), tranf- 

 parent (Aikin). It fcratches glafs with difficulty; it is 

 brittle and eafily frangible. Specific gravity 4.6 to 4.9. 

 Infufible before the blow-pipe, but changes from grey to 

 yellow. According to Klaproth, the conftituent parts are, 



Oxyd of cerium ... 54.5 



Silex ..... 34.5 



Oxyd of iron .... 3.^ 



Lime ..... 1.2 



Water - . - . . j.o 



98.7 



Cerium occurs in a bed of copper pyrites, fituated in 

 gneifs, near Riddarhytta, in Weftmannland, Sweden. 



Ceylanite, Fleonajle, Haiiy, is clafTed with the ruby 

 family by Werner : its colours are a muddy dark.blue and 

 greyifh-black, which approaches to iron-black : it occurs in 

 grains and in fmall cryttals,either perfeft ottahedrons or trun- 

 cated on the edges, or with the angles acuminated by four 

 planes, which are fet on the lateral planes, alfo in rhom. 

 boidal dodecahedrons. The cryftals are fmooth and 

 fplendent : it is tranflucent on the edges. The fratlurc is flat 

 conchoidal : it fcratches quartz. Before the blow-pipe, it is 

 infufible. The fpecific gravity of ceylanite is 3.8. Accord- 

 ing to Berzelius, the conftituent parts are, 



Alumine . . 27.25 



Magnefia . . 14-63 



Silex ... J. 48 



Oxyd of iron - - 4.26 



5 1. 62 



This mineral was firft found in the ifland of Ceylon, 

 where it occurs in the fands of rivers with tourmaline, 

 zircon, fapphire, and iron-faud. It occurs in lava from 

 Vefuvias, with olivine, augit, and mica. It occurs alfo 

 in bafalt, near Andcrnach, on the Rhine. 



CnABASiE and Chabajite. See Zeolite. 



Chalcedony. See Chalcedony- and Quartz. 



Chalk. See Chalk, and Geology, Addenda. 



Chert, a variety of horn.flone : it diflfers from flint prin- 

 cipally by being more opaque, and having lefs luftre ; it 

 occurs in nodules and malfes in the fand under the qhalk 

 formation, and in beds in fome mountain lime.ftor.e. 



Ciiiastolite, or HoIIoiu Spar, occurs cryftallized in 

 flender rhomboidal prifms, the edges of which are fometimes 



rounded. 



