MINERALOGY. 



493 



tph- 



Orrcto.no- edged in the great, but tabular in the small. Opaque. 



IT Soils slightly. Very soft, passing into friable. 

 < - Y""' tile, and uncommonly easily frangible. Feels very 

 fine, but not greasy. 



Chemical Character*. It effervesces most violently 

 with acids. 



Cuiatituent Pjrtt.Litae, 



Carbonic Acid, 39.0 

 Silica, 5.715 



Oxide of Iron, S.^85 

 Water, . 1.0100.5 



Bucholz. 



Geognoslic Situation. It occurs in nests, disseminat- 

 ed, or in small veins, in fleets or secondary lime- stone, 

 and irypsuin. 



(. graphic Situation. It is found in Thuringia and 

 Heuia. 



Second Kind. 



SLATY APHRITK, Jameioa. Schaumschiefer, Frietle- 

 ben. 



External Character* Colours snow white, passing 

 into yellowish, reddish, and silver-white. Occurs 

 masiive, seldom coarsely disseminated. Strongly 

 glimmering, sometimes approaching to glistening, evtn 

 to shining ; luitre pearly ; which sometimes pan>ea in- 

 to semi- metallic. Slaty in the great, but undulating 

 curved foliated in the small. Splits very ea*ily into 

 extremely thin tabular fragments. Opaque, or very 

 feebly translucent in the thinnest folia. Soils pretty 

 strongly. Feels soft, and rather silky. Flexible in 

 thin plates. 



Chemical Character*. It falls into pieces with a 

 crackling noise, when put into water. When touched 

 with an acid, it effervesces with great violence, and is 

 entirely dissolved in it. 



Geoenoitic and Geographic Situation* It occurs 

 naasive, imbedded, and in veins, in the first flcrtz lime- 

 stone, in Thuringia and Hessia. 



Third Kind. 

 SPARRY \rHxnc, Jamtton. Schaiimpath,FVi<:jMcn. 



External Character* Colours snow, yellowish, and 

 greyish-white. Seldom occurs massive, generally dis- 

 seminated , sometimes in flaky- crusts, in vein*, or im- 

 bedded in Urge cryUls of selenite. Shining, some- 

 time* i! i iii.inj: tn .p'rinleiit, sometimes to glistening ; 

 lustre perly, winch inclines to vitreous in the splen- 

 dent varieties. Fracture foliated, sometimes straight, 

 sometimes curved, and the tolia have a single distinct 

 cleavage. Opaque ; feebly translucent in thin pieces. 

 Occurs in large and small granular dutir.ct concre- 

 tions. Soils slightly, with glimmering dusty particles. 

 Soft. tactile. 



Chemical Character*. The same as in the other 

 kinds. 



tfotiic Situation. It occurs in floMz or secondary 

 limestone and gypsum. According to Friesleben, it 

 appear* to be geogno>.tically allied to selenite ; and al- 

 though it differs from that mineral in colour, transpa- 

 rency, lustre, sectility, feel, and effervescence with 

 acids, yet it passes into it, and also into slaty aphrite, 

 sometime* by simple gradations, sometimes by inter- 

 mixture of tin- twi, miner.ils ; and large lenticular crys- 

 tals ol'selrnite occur, which are pure at the edges, be- 

 come gradually more opaque towards the centre, and in 

 the centre are pure uparry aphrite. 



Geographic Situation It occurs in Thuringia. 



TENTH SUBSPECIES. 



I.cci LUTE, Jameton. 



This subspecies is divided into three kinds, vi. 

 Compact Lucullite, Prismatic Lucullite, and Foliated 

 Lucullite. 



Firtt Kind. 



COMPACT LUCULLITB, Jameton Dichter Lucullan, 

 J'Jtn. 



This kind is divided into Common Compact Lucul- 

 lite or Black Marble, and Stinkstone. 



a. COMMON COMPACT LUCULLITE, or BLACK MARBLE, 

 Jameson. 



External Character*. Colour greyish-black. Oc- 

 curs massive. Internally strongly glimmering, inclin- 

 ing to glistening. Fracture fine-grained uneven, and 

 large conchoidaT. Fragments indeterminate angular, 

 and ratner sharp-e-Jged. Opaque. Semi-hard. Yields 

 a dark ash-grey coloured streak. Brittle, and easily 

 frangible. 



When two nieces are rubbed against each other, a fe- 

 tid uriuous odour is exhaled, the intensity of which is 

 increased when we at the same time breathe on them. 



Chemical Characters. It is infusible without addi- 

 tion. When exposed to a high temperature in an open 

 crucible, it burns white. With sulphuric acid, it forms 

 black-coloured mass : it dissolves in nitrous and mu- 

 riatic acids, but leaves an insoluble black-coloured sub- 

 stance. During the solution and escape of the carbo- 

 nic acid, a mell resembling that of sulphuretted hy- 

 drogen is evolved. 



Contlituent Part*. 



Lime, - 53.38 



(\rbnnic Acid, - - 41.50 



Black Oxide of Carbon, - 0.75 



Magnesia, and Oxide of Manganese, 0.12 

 Oxide of Iron, - - 0.25 



Silica, - - 1.13 



Sulphur, - - 0.85 



Potash, combinations of Muriatic and 



Sulphuric Acids, and Water, 2.62 100.00 



Jo/in, Chem. Laborat. b. ii. s. 240. 



Geognailic Situation __ Tin geogiiostic relations of 



this mineral are still but luilr known : it is said to oc- 



cur in beds in primitive and older secondary rocks. 



Geograph'C Situation Hills of this iiiiiu r.d occur in 

 the district of Atvynt in Sutherland. Varieties ol it 

 are met with at Ashlord, Mallock, ,.nd Mons :ldale, in 

 Derbyshire : at Kilkenny; at Crayleath,in the County 

 of Down j at Kilcrump, in the county ut Wuteriord; at 

 Churchtown, in the county ot Cork ; and in the coun- 

 ty ot Gal way, in Ireland. 



Ute*. The finer varieties of this mineral have been 

 highly prized, and used aa marble truni a very it-mote 

 period. It was so much adunrtil ;mu i -Unmd by the 

 Consul Lucullus, that he g-ive it his nun name, i'liny 

 observes: " Post hunc Lepiduni ferine quadriennio 

 L. LucullusConsulfuit,quiiHpimi,(ut. ppartt t-x re , /.i<- 

 culleo Marmori dedit, auinoduin ilelt-cutus illo, primus. 

 ijuc Romam invexit, atrum ulioqui, cum catera macu- 

 lis aut coloribus coinnu inn i.tui. Nascitur autem in 

 Nili insula, solumqut horum inarinoiuiu ab amaiure 

 nomen accepit. 



The finest varieties of lucullite met with in trade in 

 thi-. island, are the black marbles of Sulherlandsbire, 

 Kilkenny, and Galway. 



Oryctogno- 

 sj. 



Luculbte. 



