50 A SYSTEM OF 



SECT. XLIV. 



B. Saphire, Saphyrus gemma. 



It is transparent, of a blue colour, and 

 is faid to be in hardnefs next to the ruby, 

 or diamond. 



are found promifcuoufly mixed, having each their different 

 forms, colours, and hardnefs, furnifhes a proof that nature 

 forms the fo called precious Hones or gems, each from its par- 

 ticular matter or principle. 



The round diamonds may be fuppofed to have undergone 

 the fame fate with fome of the rock criftals, viz. to have 

 been, by changes in the earth, broken from their beds, and 

 by the agitation of waters, ground and rubbed againft one 

 another, until they have been rounded or reduced to this 

 form ; fince they are moftly found amongft fand, and are dis- 

 covered in places worn down by heavy (bowers of rain. 



The ruby is criflallifed into an ccloedral form, as well as 

 the diamond *, and differs al fo very little from it in hardnefs 

 and weight ; I have, therefore, confidered thefe two, as be- 

 ing of one and the fame kind, and that with as much right 

 as others, who have ranked them under the rock criftals, 

 which lafl are mere regular than any other earthy fubftance, 

 as they affume, during their criftallifation, a determined 

 form, viz. the hexagonal, "with a point at one or both ends. 



A fort of diamond is found, which is faid to be very foft, 

 and is called the jargon f, but this fort is Hill unknown to 

 me, nor have I found that any experiments have been made 

 relating to its hardnefs and principles. 



I have feen in the collection of the mine-maftcr, M. Van 

 Swab, a diaphanous adoeJral critlal of fluor, which, ac- 

 cording to thofe, who only mind the figure, ought to be 

 called a Diamond. 



* What I have obferved about the ocloedral form of the diamonds, 

 imayalfobe applied to the rubies. Bcfides, the lubies aie alio femetimes 

 found of itregular hexagonal figures. E. 



f The Jargon, fo called by the Englifh jewellers. Its natural fhape is 

 not yet known, it being found in form of pebbles in the Indies, where it 

 is fpJit into thin pieces, and thus fent to Europe. The jargons are of dif- 

 ferent colours, viz. white, light yellow, and brown. According to 

 fome lapidaries, they come ncareft to the Captures in hardnefs ; and as 

 they have, when cut and polifhed, a great refemblance to the diamond, 

 they are alfo by fome called Soft Diamonds, and one may eafily be im- 

 pofed upon in puichafing thefe for true diamonds, when they are made 

 up in any fort of jeweller's work. E, 



In 



