Sulphate of Barytes
- Div. 2. Imitative.
When we are showing any distinct subject, it is often necessary, for the sake of comparison, to exhibit others that bear analogy to it, and may be confounded with it, Frederick Hall, Esq., whose kindness gave me an opportunity of showing the best specimen of crystallized Carbonate of Barytes, tab. 76, favoured me with this specimen of Sulphate from Arkendale in September 1805. It now seems to be an appropriate time to exhibit this, and the pleasure I have in doing so may perhaps only be felt by those who occasionally share such friendly favours. It is, if I may use the term, a vermiculated Sulphate of Barytes, or somewhat like Sabella rudis, which accumulates bits of shells, as if an abundance of worm gluten, having accumulated every thing in its way, found chiefly Sulphate of Barytes to adhere to it. It is composed of irregularly formed tubes, many of which are distinctly angular with from three to five angles, the tubes curving and passing over each other in every direction in a crowded manner. When the present specimen was sent, Mr. Hall observed he could have sent a very large mass but for the great weight and bulk, it being as big as a bushel.
Primitive Crystals of Sulphate of Barytes are rather rare. These tubes are nearly covered with them both on the inside and out, the tubes being rather opaque. Those within are smallest, and most irregular; of the outer ones some are nearly perfect; others slipped off, if I may use the expression; and the nuclei falling on each other somewhat irregularly are lengthened out beyond the proper angle; some are a little rounded, and some flattish; others have truncations on their angles, &c.—see fig. 1, 2, 3, 4.—and in some instances resemble the Pearl-spar, tab. 19.
I have a specimen that was in the collection of my late lamented friend Mr, Day, from Matlock, that has quartzose tubes which have much the appearance of the Coral, tab. 292, each surrounded by Cubic Fluor and Sulphate of Barytes in nearly lenticular crytals, like tab. 96.