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COMMON AUGITE. 55 gite ; it becomes electrical by heating, but augite does not; and schorl is more easily fusible than augite.— c. Between cross twin-crystals of Augite, and cross crys tals of Grenalite. In grenatite, the crystals cross each other under angles of 60° and 90° ; in augite, they cross each other less determinately.—d. Between Augite and Olivine. In olivine, the colours are lighter, the crystal lizations are different, and the hardness and specific gra vity less considerable than in augite.—e. Between Augite and Epidote. In epidote, the green colours are lighter than those of augite: further, its crystallizations, and cleavage, are not the same; and in general, it is a more transparent mineral. 2. It is by Werner divided into four subspecies, viz. Granular, Foliated, Conchoidal, and Common ; and the following are a few of the characters used by him in their description : (1.) Granular Augite.—Colour is greenish black. Oc curs massive ; and crystallised in the following figures: 1. Broad six-sided prism, with two opposite acute late ral edges; and generally flatly bevelled on the extremi- tles - 2. Six-sided prism, acuminated with four planes, which are set on tire obtuse lateral edges. 3. Six-sided prism, with convex terminal planes. 4. N° 1. trun cated on the acute lateral edges. When these increase, so as to be of equal magnitude with the lateral planes, there is formed, 5. A broad and nearly equiangular eight-sided prism, (j. When the two broader lateral planes of N° 1, disappear, a four-sided prism is form ed. Crystals seldom perfectly sharp-edged; general ly superimposed, and form druses. Internally glisten ing, and resinous. Fracture imperfect foliated, or un even. Occurs in large and small angulo-granular distinct I) concretions.