[ 3 



prifms, with trihedral fummits. Anal. Silex 

 57. Argill 35. Oxyde of iron and manganefe 



5. Bindheim. 



u. Amethyst, cryftallized in hexahedral prifms, 

 with correfponding pyramids ; of various degrees 

 of tranfparency, and colour. Anal. Silex 30. 

 Argill 60. Lime 22. Iron 1,66. A chard. 



v. Quartz, cryftallized in double hexahedral 

 pyramids, with or without an intermediate prifm ; 

 of various fhapes ; ftrikes fire with fteel; is folu- 

 ble in fluoric, but not in nitric or muriatic acid ; 

 Anal. Silex 93. Argill 6. Lime 1. Bergman. 



w. Prase, of a leek green colour ; cryftallized 

 in fix-fided prifms, acuminated by fix faces, pro- 

 ceeding from die fides of the prifms. 



x. Elastic Quartz, amorphous, angular. Anal. 

 Silex 0,965. Argill 0,025. Iron 0,01. Klaproth, 



y. Obsidian, Iceland Agate, of a greyifh or 

 blackifh colour ; found in irregular fhaped pie- 

 ces. Anal. Silex 69. Argill 22. Iron 0,009. 

 Bergman. 



z. Cakedony, Cornelian, Agate, called CaU 

 cedon, from the name of a place; ufually found 

 in folid maffes, of a globular, kidney-like, or fta- 

 laftical figure, or in the ftate of pebbles ; fome- 

 times filiform, tabular or cellular; of a greyifh, 

 yellowilh, white, or milk white colour. Anal. 

 Silex 84, Argill 16. Bergman. 



R a a* Chryso* 



