Sulphate of Lime, or Gypsum

Spiculated Gypsum is also new in description, as far as I know; and from what has been said, such a thing could hardly be expected. It is, however, necessary that any mineral should be known, in whatever form or variety it maybe; and Gypsum being at present so much recommended as a manure, makes it not less necessary, as otherwise Gypsum might be brought to manure Gypsum, or be refused by those who prepare it, as useless.

This is a pretty and delicate variety. The crystals are much confused, but seem to be a mass of trapeziums—see tab. 67—piled or formed into little spires; the points of the trapeziums being mostly inclining upwards. It came from Derbyshire. The under specimen might be considered as a red or rose-coloured Gypsum. They are often coloured with red Oxide of Iron, in various degrees. This specimen appears of rather an uncommon form; the crystals are something like the above, but lie horizontally; and it would seem as if the whole was a sort of Stalagmite, having fallen into this form in a particular state.

I received this specimen by favour of my kind friend Dr. P. Murray, from the limestone quarry at Bilton in Yorkshire, along with another very instructive one, part of a larger mass, with a vein of whiter striated Gypsum passing into it, holding almost orange-coloured, or deeper tinged, perhaps, primitive rhombs within it—see the left hand figure and right hand geometrical one. This variety is sometimes compact and hard enough to be turned and polished for ornaments.