88 CLINTONITE. 



BB deflagrates, emits arsenical fumes, 

 and fuses readily, yielding a globule of cop- 

 per. 



Soluble in acids and ammonia. 



Localities. Near St. Day, Cornwall, at 

 Ting Tang Mine, Hue! Unity and Huel Gor- 

 land, and at Bedford United Mines, near 

 Tavistock. The crystals usually present a 

 very dark blue colour and a brilliant lustre, 

 but are rarely recognisable, being aggre- 

 gated in diverging groups, or disposed in 

 extremelv minute individuals in cavities of 

 Quartz (Allan). 



Name. From xX'tvu, to incline, and aKac^^ 

 to break, in allusion to the oblique cleavage. 



Brit. Mus., Case 56. 



31. P G. Principal floor, Wall-case 2 

 (British). 



CLi>rTONiTE, Mather. Generally occurs 

 in tabular crystals, or in thinly foliated 

 masses which are micaceous parallel to the 

 base. Colour yellowish, reddish-brown or 

 copper-red, with a pearly submetallic lus- 

 tre. Streak white, or slightly vellowish or 

 greyish. Brittle. H. 4 to 5. S.G. 3 to 3-1. 



Coinp. (m^ + ^iv) 



Si^lf + iH. 



Anali/sis, bv G. 



H. Brush : 



Silica ."' . 





. 20-24 



Alumina 





. 39-13 



Zirconia 





. 0-75 



Lime . 





. 13-69 



Magnesia 





. 20-34 



Soda . 





. 1-14 



Potash . 





. 0-29 



Peroxide of iron 



. 327 



Water . 





. 1-04 



100-39 



BB alone infusible ; but whitens, and with 

 borax or soda forms a transparent pearl. 



Locality. Amity, New York, U.S. ; in 

 limestone with Serpentine, associated with 

 Hornblende, Spinel, Pyroxene and Gra- 

 phite. 



Name. After the Hon. De Witt Clin- 

 ton. 



Cloudy Chalcedony. Chalcedony dis- 

 playing dark ana clouded spots in a pale grey 

 transparent base. 



Cluthalite, Thomson. The mineral 

 named Cluthalite by Thomson, which oc- 

 cui's in flesh-red, vitreous crystals in amyg- 

 daloid at the Kilpatrick Hills, is Anal- 

 cime, with half of the soda replaced by prot- 

 oxide of iron, and with a larger amount 

 of water. H. 3-5. S.G. 2-166. 



Analysis, by Thomson : 



Silica 51-266 



Alumina „ „ . . 23-560 



COAL. 



Protoxide of iron 

 Soda . 

 INIagnesia . 

 Water 



7-306 



5-130 



1-233 



10-553 



99048 



Name. After Clulha, a name by which 

 the valley of the Clyde has been sometimes 

 distinguished. 



3LP.G. Horse -shoe Case, No. 1185. 



Coal is vegetable matterwhich has become 

 mineralized by certain chemical changes 

 which it has undergone, and by subsequent 

 solidification by compression under the 

 weight of the strata which have been ac- 

 cumulated above it since it was originally 

 deposited. It appears to be composed of 

 terrestrial and aquatic plants and trees, (the 

 decay of which probably reduced them to 

 peat,) which grew in a warm and moist 

 climate of equable temperature, on the 

 areas it now occupies, close to, or perhaps in, 

 the margin of a shallow sea ; and the clay 

 (^Uiiderclay) with the roots of plants {Stig- 

 maria, §-c.) supporting each bed of coal, is the 

 soil on which the vegetation grew of which 

 it is formed. Each separate bed of coal, on 

 this supposition, denotes the former exist- 

 ence of an adjoining surface of land, on the 

 depression of vvhicli beneath a sea of moderate 

 depth, the vegetable matter growing upon 

 it became covered up by a deposit of sedi - 

 ment which in its turn, by the further 

 deposit of sediment and oscillation of level, 

 supported a fresh growth of vegetation. In 

 this manner, by a series of depressions of mo- 

 derate amoimt, each bed of coal was formed 

 in succession, while its interstratification 

 with beds of limestone, shale, clay, sandstone 

 and ironstone indicates alternations of ma- 

 rine, estuary and lagoon conditions. Although 

 coal for the most part appears to have been 

 formed in the above-mentioned manner, it 

 is probable that other conditions may have 

 occasionally prevailed, as for instance in the 

 north of England and in the south of Russia, 

 where some of the coal beds are stated to be 

 apparently composed of the remains of 

 broken and drifted plants carried into the 

 sea by inundations, and the freshets of rivers. 



Coal is composed of Carbon, Hydrogen, 

 Nitrogen, Oxygen, Sulphur, and earthy 

 matter or Ash, in variable proportions. The 

 greater the proportions of Carbon and Hy- 

 drogen the better is the coal, while sulphur 

 and ash tend to render the coal both un- 

 pleasant to use, and prejudicial in its efi"ects, 

 especially in the smelting of iron and steel. 



Coals may be divided into two classes — 

 bituminous and nonbituminous or Anthra- 



