in natural history, a genus of talcs composed of large plates visibly separate, and of extreme thinness; and each fissile again separated into a number of plates still finer.

Of this genus there are three species. 1. The white shining specularis, with large and broad leaves, commonly called fling-glasfs and Mulcovy-glasfs: its lamellae, or leaves, are extremely thin, elastic, and transparent; it makes not the least effervescence with aqua-fortis, and is not easily calcined in the fire. It is imported in great quantities: the miniature painters cover their pictures with it; the lantern-makers sometimes use it instead of horn; and minute objects are usually preferred between two plates of it, for examination by the microscope. 2. The bright brown specularis, with broad leaves; a very valuable species, though inferior to the former. 3. The purple bright specularis, with broad leaves; which is the most elegant of all the talcs, and not less beautifully transparent than the first kind.