30 HORNBLENDE FAMILY. Observations. 1. Asbestous Tremolite might be confounded with Amianthus; blit the following distinctive characters will enable us to discriminate them with facility :—The frac ture of amianthus is parallel and curved fibrous, but that of asbestous tremolite is scopiform fibrous: amianthus does not occur in distinct concretions, as is the case with asbestous tremolite ; the powder of amianthus is soft, whereas that of asbestous tremolite is dry and rough to the feel; and, lastly, amianthus is not phosphoric by friction, whereas asbestous tremolite becomes phosphoric by friction. 2. Hauy now considers tremolite but as a variety of aetynolite, and actynolite as a variety of hornblende; consequently he arranges these three minerals under one head, as a single species, under the name Amphibolc. Bournon having proved that these minerals do not agree in their primitive forms, and Werner having shewn their difference in other characters, we are still inclined to con sider them as distinct species. 3. On a general view, Tremolite is characterised by its white colours: Actynolite by its light green colours; and Hornblende by its dark green colours. 4. Kyanite,