Sulphate of Barytes
- Class 2. Earths.
- Order 1. Homogeneous.
- Gen. 6. Barytes.
- Spec. 1. Sulphate.
- Div. Crystallized.
Sulphate of Barytes from Surry seems not very generally known: I was first informed of it by my kind friend Mr. Warburton. It is perhaps rather remarkable for its bright brown or candied sugar tint, and, I may also say, for its being suspended in the midst of the Fuller’s Earth—see descr. of tab. 231—in masses of about 100 pounds in weighty the whole generally very irregular on the outside, and more or less coated with Ochre, and incorporated with the Fuller’s Earth, which is not so pure within two or three feet of it, therefore the proprietors of the pits do not desire to meet often with this Sulphate.
When these lumps are broken they are found to be a mass of different-sized crystals, crossing and interrupting each other continually, and sometimes distinct, of various modifications. I was, it seems, particularly fortunate in what I met with when I visited the place in 1805. I found in two lumps most of the modifications from and with the primitive, including two facets not yet mentioned by any author. One part of the lump was particularly beautiful. The annexed figure is taken from a fragment of it, and will give an idea of the manner in which they lie. The darker sides of the prisms with the Pyrites* are chiefly primitives. The broader white† faces are truncations, as it were, of these, and have little irregular cavities with somewhat stellated Carbonate of Copper, On some sides there are minute, bright, iridesccntly golden-tinged, rust-coloured rhombs of Carbonate of Lime, which Count de Bournon took notice of in my museum when admiring the specimen. There are also darker ones passing to dark brown, and nearly or quite black. Some very pale Amethystine Quartz is occasionally found in the interstices, which sometimes has the impression of the Barytes.
The faces in this specimen are best to be understood by the geometrical figure.
Since writing the above I have met with a specimen in which an interrupted crystal about six inches long lies partly imbedded in the gangue of the same, and is of a very fine strong bright vinegar colour, but so well relieved as to appear equally bright, if not brighter, than the finest jewel set on foil.
- * The Pyrites, which is generally of a brassy yellow, was found from the octaëdron to the cubo-octaëdron in much variety, elegantly embossing the faces.
- † The opaque whiteness of the faces seems to be a crystallization with a smaller proportion of the water or solvent.