Jasper Enlarge
July 1. 1807. Publish’d by Ja.s Sowerby London.
British Mineralogy
Silex Quartzum; var. Jaspis


  • Class 2. Earths.
  • Order 1. Homogeneous.
  • Gen. 4. Silex.
  • Spec. 1. Quartzum.
  • Div. 1. Crystallized.
  • Syn.
    • Iron Flint. Jameson, v. 1. p. 134.
    • Eizen Keisel. Werner.

This has an appearance so peculiar, that it may be readily distinguished when once seen, although on careful examination it will be found to differ very little, if at all, from the other coloured Jaspers, either in its nature or component parts. It is said to be crystallized, like Quartz, with the pyramids terminating in three faces, and sometimes with the other three belonging to Quartz very small*. The fact is, that this substance is no other than Quartz with a red or yellow Oxide of Iron, and is often partially crystallized, though sometimes otherwise with an appearance rather peculiar, which occasionally resembles a coarse red sealing-wax, or the cement used by lapidaries, made of pitch, resin, and brick-dust. Its hardness is the same as that of Quartz. Us peculiarity at first sight has been sufficient to make those who have found it, and who were pretty well versed in the science of Mineralogy, inquire what it was; and Werner, I suppose, seems satisfied that it ought to have a name which might distinguish it.

The specimen figured comes from Bristol, and I have some also from near Keswick, in Cumberland. I believe it is not very rare. The lower geometrical figures are intended to show the forms of the crystals as above mentioned.

  • * We have independent crystals of Quartz from Matlock, &c. of the same form.
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