EARTHS. SILICEOUS. 54.. Arena. 



i6t 



Sahulum^ 



snicacea. 



rustica. 



colorata. 



Glared, 



B. Compofed of comminuted quartz, 



Confifting of angular unequal largers grains. Gravel* 



Arena heterogenea. Sy/I, nat. xii. 3. p. 198. n. 9. 

 Arena faxofa. Wall, fist, min. i . p% 106. ». 7. 

 Found every where on barren rocky mountains, and is produ- 

 ced by granite which has mouldered from expofure to the 

 air, and is frequently found mixed with particles of mica, 

 feirpar and argil. It is principally afed for gravel walks. 



Shining with numerous interfperfed fmall fcalcs of mica, 

 refembling thin plates of gold or filver in colour and 

 luftre. 

 Arena micacea. S^yfi. nat. xii, 3.^. 198. n, 11, 

 Arena micacea. Wall.fysts min. i. p, 105. «, 6. 



2. Arena Caflerita. Syst,nat, xii. 3.^. igfi.n.iz. 



Found in S-weden and Germany^ 2) in the ifland CaJJerita, and 

 is compofed of comminuted granite and other like Hones. It 

 is the fand ufed to dry up the ink on newly written letters. 



Confifting of roundifh unequal larger grains. 

 Arena heterogenea. «S'vj7. nat. xii. 3.^. 197. ». 8. 

 Arena quartzofa. Wall, miner. 33. 

 Common fand. SchmeiJJ'er miner aU i. /. 337. 

 Found every where in Europe^ principally upon fhores, and 



contains fome lamellar particles apparently of quartz. It ii 



ufedTor gravelling walks. 



In rounded minute femitranfparent grains tinged with 

 oxyde of iron. 

 Arena quartzofa. Syst. nat. xii. 3. />, 196. n. 2. 



2- Arena ochracea, Syst. nat. xii. 3./). 197. ». 7, 



3. Arena lacuftris, Syfi. nat, xii. 3. p. 197. «. 3. 



Found in South America and Europe., principally on the (hores of 

 lakes : colour yellow, yellowifh, or teftaceous, rarely red, 

 violet in the Baltic near Germany, It is ufed for fprinkling 

 over letter?, and makes admirable gravel walks. 



In very minute grains mixed vv^ith puVerlfed alumina. 

 Arena fubfarinacea. Syit. nat. xii. 3. /, 197. «. 6. 

 Glarea partic, inequal. Waller Jy/i, i, p. 87. «. 2. 



2. Glarea fterilis fuforia. Wall. min. 31.3. 



Glarea partic. fubtiliif. WalLfyfi. 1 . p. 86. n. i . 

 Duft fand. Grit. Schmeifser miner. \^ p,'^'^6, 



VOL, vir, — X 



