126 
EARTHS. ARGILLACEOUS. 36. Bafalies. 
36. BASALTES, Confining of a large proportion 
of fihca, with a kfler prop' .rtion of alumina and 
oxyde of iron, and often a little lime, magnefia, 
oxyde of manganeie and ibda: opake, inconfpi- 
cuoiis, meagre, generally becoming greyifh when 
robbed with a knife, breaking into indeterminate 
fragments, mouldering in the air into argil: not 
effervefcing with nitric acid, melting before 
the blow-pipe into a black glafs attiafted by the 
magnet. 
schlaoiu!. Black, of a Oafy texture. 
Found in bafaltine mountains on ihz Rbirre, and in tke neigh- 
bourhood of GnUin^en, cnmraonly abounding in particles of 
Olivin, 
n^Iumnniri!, Of a dull Colour, compttcl, harclifli, tenacious, fpontanc- 
oufly breaking into prilmatic granular fragments. 
Rafultes. Baum miner, i. p. 220. 
Ilalaltcs ftgura columnari. tf'alL fyH. 1. p. 319. n. 9. 
1 ' igurate Trap, Falalt. Kirwsinminir. \ , p 231. 
lialalt. Scbmeijjer min. I p 185. Ihomfins chim. 3. p. 373. 
Found in various parts of the Brit Jh Ifiands, particularly in 
Staffa in Scotland, and site Giem's Cauftiway in Ireland, in the 
Bouth Sea IJlmds, Sia/y, Ituly, France, and many parts of 
Europe, generally forming the hafe of mountains, of a co- 
lumnar th-pc, ilraight or curved, perpendicular or inclined, 
rarely parallel ; the diameter of tke columns from 3 inches to 
3 feet, iuinetiines with tranfverfe femifpherical joints, in 
which tlie conveitty of one is inferred into the concavitv of 
the other; their form is pentangular, hexangular, or odfan- 
giiiar, rarely triangular, or quadrangular: colour blueilh or 
grecnilh-black, ordark grcyifh-blue, varioufly iuterfeaed with 
veins of white calcareous ipar, and often the imprclhons of 
various fotfile bodies and fhruhs; they are rather hard and 
difficult to break, feel harlh, and found under the hammer: 
texture earthy ; fraiture uneven ; ftreak alliy-grey: fpecific 
gravity from 2,864. to 3,000. a fpecimen from Staffa con- 
tained fiiica 44. alumina 16. oxyde of iron 16. lime 9. 
water 5. foda 4. muriatic acid t. Kennedy, 
pyratnidalis Of a dull colour, compafi, fpontaneoully falling into py- 
ramidal fi-agments. 
Ilacquet Chevi. 'Journ. 1788. I. p. 522. 
Found in the mountains of Bohemia, ncAT in elongated 
5-fidtd fragments j and in Hungary, near Sebemniz. and Lrem~ 
i(!z, in 4-fided fragments. 
