GEM. 
GENERIC CHARACTER. 
A very hard and almost infusible stone, composed of 
siliceous and argillaceous earth, mixed with a little calx 
and iron. 
RUBY. 
SPECIFIC CHARACTER. 
Gemma Rubinus. G. durissima ponderosa rubra, texturae lamel- 
losae, directione mutata conchaceae, coloris 
in igne et tritura tenacissima. Linn. Syst. 
Nat. Gmel. 3. p. 170 . 
A very hard, heavy, red gem, of a lamellated 
texture, changing to the conchoidal ; re- 
tains its colour in the fire, and also when 
ground to powder. 
Gemma pellucidissima duritie secunda, colore 
rubro in igne permanente. Waller. Miner. 
111. Syst. Miner. 1. p. 325. no. 2. 
Rubinus. Vogel. Miner. 143. Baum. 
Miner. 1 . p. 22. 
Ruby. .... Cronst. Miner. 1 . p. 134. Kina an, Miner. 1 . 
p. 250. Patrin, Hist. Nat. des Miner. 1 . 
p. 243. Brongn. Miner. 1 . p. 436. 
We are told by Patrin that the oriental ruby, the 
oriental topaz, and the oriental sapphire, which 
