Sandstone Enlarge
Apl 1 1811 published by Js Sowerby London.
British Mineralogy
Silex quartzum, arenaceum


The beautifully eyed Sandstone, which will be figured hereafter, is in a great measure elucidated by these small globular ball-like Sandstones from Charlton Sand-pits, with which I am favoured by Lady Wilson. They appear to be caused by the oxidation of Iron, perhaps from Sulphuret of Iron, being spread by means of moisture among the particles of Sand in certain proportions. There is, however, something remarkable, that the centres of most of these specimens are nearly pure sand-form white Silex with a narrow deep-coloured margin; a sandy ochraceous crust succeeds, which is covered by a broader one very uniformly spherical, and sometimes two or more spheres coalesce or are in contact.

The lower right hand figure is from Yorkshire, by favour of Mr. Danby, and shows the Oxide of Iron in small spots; and I have such from North Wales, &c. The lower left hand figure shows another variety, where the small spots are not ochraceous but surrounded by the Red Oxide of Iron, Beautifully striped Sandstones also often occur. Something like this, much indurated and nearly allied to Jasper, is found at Salisbury Craig near Edinburgh.

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