Page:Theophrastus - History of Stones - Hill (1774).djvu/155

  ditinguih it into two Kinds, the Spring Crytal; and Pebble Crytal. The firt is found in the perpendicular Fiures of Strata, commonly in Form of an hexangular Column, adhering to the Matter of the Stratum at its Bae, and terminating at its other End in a Point. The other is found lodged at random, in the tony or earthy Strata, or looe among Gravel, and is of no certain or determinate Shape or Size, but reembles the common Flints or Pebbles in Form.

There are, beide thee, regular and hexangular Crytals, found alo lodged in the Strata, ometimes pointed at both Ends, ometimes covering the external Surface of mall roundih Nodules, and ometimes hot all over the Inide, of hollow ones of various Sizes: Thee lat are called the echinated and concave crytalline Balls; and the former the double-pointed Crytal, Crytallus in acumen utrinque definens. The Pebble Crytals of England are often of very coniderable Hardnes; and ome have been found here which the Lapidaries have aid approached to the white Sapphire. The pointed and hexangular are what Authors have called Iris's and Peudo-adamantes. The Antients were of opinion, that Crytal 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 exceively cold Regions; but we are now very certain, that it is even in the hottet. As to the various Forms of Crytal, they will be no where o well known, as from the Crytallographie of the great and incomparable De L'ile. Amethyt; both which are, in like manner, pellucid,

LV. Thee, as alo the Carnelian, are ometimes found in the dividing other Stones.