rock-wood, or ligneous asbestus. 585 The fragments are tabular. It becomes shining in the streak. It is soft, passing into very soft. It is opaque. It is sectile. It is rather difficultly frangible. It is slightly elastic-flexible. It feels meagre. It creaks when we handle it. Specific gravity, 2.051, Wiedematf. Chemical Character. It is infusible before the blowpipe. Geognostic and Geographio Situations. It occurs at Sterzing in the Tyrol, along with many different fossils, as common asbestus, actynolite, quartz, garnet, blende, iron-pyrites, galena, and calamine; and its repository, as Mobs remarks, appears to be a bed, as it is accompanied with minerals that often occur in such situations. It is also found in Dauphiny, and in Stiria; and Steflens conjectures, from the descriptions of Georgi, that it occurs in different places in the mountains of Archangel and Olocnezk. Observations. It is distinguished from Rock-Cork, by its wood-brown colour, higher lustre, and double fracture, being curved slaty in the large, and delicate fibrous in the small. 7. Picrolite.