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[1]Amethyſt; both which are, in like manner, pellucid,
LV. Theſe, as alſo the Carnelian, are ſometimes found in the dividing other Stones.
- ↑ The Amethyſt of the Antients was the ſame with the Gem known yet by that Name: It is a very elegant Stone, of a purple or violet Colour, in different Degrees of Deepneſs. It is found both in the Fiſſures, and lodged among the Matter of the Strata; and fometimes, like common Cryſtal, in concave Balls, reſembling the Ætitæ. It owes its Colour to Iron: And common Cryſtal and Spar are often found in and about Mines of that Metal, tinged in different Degrees to a Reſemblance of it. The Antients reckoned five Species of the Amethyſt, differing in Degrees of Colour; and we have at leaſt as
daries diſtinguiſh it into two Kinds, the Spring Cryſtal; and Pebble Cryſtal. The firſt is found in the perpendicular Fiſſures of Strata, commonly in Form of an hexangular Column, adhering to the Matter of the Stratum at its Baſe, and terminating at its other End in a Point. The other is found lodged at random, in the ſtony or earthy Strata, or looſe among Gravel, and is of no certain or determinate Shape or Size, but reſembles the common Flints or Pebbles in Form.
There are, beſide theſe, regular and hexangular Cryſtals, found alſo lodged in the Strata, ſometimes pointed at both Ends, ſometimes covering the external Surface of ſmall roundiſh Nodules, and ſometimes ſhot all over the Inſide, of hollow ones of various Sizes: Theſe laſt are called the echinated and concave cryſtalline Balls; and the former the double-pointed Cryſtal, Cryſtallus in acumen utrinque definens. The Pebble Cryſtals of England are often of very conſiderable Hardneſs; and ſome have been found here which the Lapidaries have ſaid approached to the white Sapphire. The pointed and hexangular are what Authors have called Iris's and Pſeudo-adamantes. The Antients were of opinion, that Cryſtal was only Water congealed in long tract of Time, into an Ice, more durable than the common. And Pliny thought it was no where to be found but in exceſſively cold Regions; but we are now very certain, that it is even in the hotteſt. As to the various Forms of Cryſtal, they will be no where ſo well known, as from the Cryſtallographie of the great and incomparable De L'iſle.
