144 EARTHS. SILICEOUS. 42. Gemma. 



foliated texture : they are imitated by heating rock cryftals 

 and putting them into a folution of dragon's-blood : con- 

 tains alumina 40. carbonate of lime 20. oxyde of iron 13, 



Bergm 



an. 



alakandica. Hard, peliucid, of a red colour, not fufible but loling its 

 colour in a itrong heat. 

 Ferber n. Beytr. mineral. i,p. 585. 



Found in the river Gogtch near Lengefeld^ in the form of rounded 

 granulations, from the fize of a pea to that of a bean : when 

 expofed in a flrong heat furrounded with wood-alhes, lofes 

 all its colour, and is often fold for the Diamond, 



Rubicellus, Hard, of a reddifli colour verging to pale yellow, not fufi- 

 ble but loling its colour in a itrong heat. 

 Rubinus col, rubeo fubflavo, Wall.Jyst. i,p. 236, «, 2. d. 

 Occidental or Brafilian Ruby. Kirivan min* i. p. 2^j^. 

 Found in the Ea/l Indies: is fofter than the Topaz, and of a 

 much inferior colour: fratlute foliated, 



Sp'nel/us, Hard, of a pale red colour inclining to orange, not fufible 

 but lofing its colour in a ftrong heat. 



Rubin, col. rubeo fubalbo. JValLjyd. I. p. 236. n, 2, c. 



Spinell and Bdlafs Ruby. Kir-wan miners \» p. 253. 



Spinell. Schmeijer miner. I. p, 61, 



Spinell. Thpmjon ckem, 3. p. 514. 



Found in Ceylon^ in 8-fided cryftals, confiding of 2 pyramids, 

 each of 4 planes, and joined bafe to bafe ; or triangular, or 

 trapezoidal plates bevilled on the edges : texture foliated : 

 frafture conchoidal : fpecific gravity from 3,570. to 3,625. 

 contains alumina 76, filica i6. magnefia 8. oxyde of iron 

 1,5. Klaproth. 



Jqua mart. Hard, pellucid, lamellar, pale fea-grecn, not fufible 

 na. per fe, breaking into trapezoidal fragments. 



Borax lapidofus. Syst. nat. xii. 3./. 95. «. 2. c. 



Smaragdus. Wall Jyji, min. 1 . p. 242. «. 5. c» 



Beryll. Kir <vj an miner, i. p. 248. 



Aquamarine, BeryL SchmeiJ/er miner . i. p. 66. 



Beryl, or Aqua Marina. Thomfon chem. $• P $$7' 



Found in Brafil^ India^ Siberioy Saxony, and Bohemia, fomc- 

 times amorphous, fometimes cryftallized in equiangular 6- 

 fided prifms longitudinally ilriated : its longitudinal frafture 

 rather conchoidal, its tranfverfe frafture toliated : colour 

 rarely a bluifh-green : it decrepitates when heated, and is 

 generally a licde difcoloured, but does not melt : becomes 

 elcttric by friftion, when one of its ends is attraftive, the 

 other repulfive : fpecific gravity from 3,521. to 39548. 

 contains filica 69. alumina 13, glucina I to. oxyde of iron 

 1. lime 0,5. yau<iuelin^ 



