a fine deep red ochre, with some admixture of purple, very heavy, and of a dense yet friable structure, and rough dusty surface. It adheres very firmly to the tongue, melts freely and easily in the mouth, is of an austere and strongly astringent taste, and stains the skin in touching. It is the Sil Atticum of the ancients; it ferments very violently with acid menstrua; by which single quality, it is sufficiently distinguished from the Sil Syricum, to which it has in many respects a great affinity. It is found in immense quantities in many parts of Spain; and in Andalusia there are in a manner whole mountains of it. It is used in paintings, and in medicine as an astringent.