kED LEAD-ORE OR CHROMATE OF LEAD. 41 1 It rarely occurs massive or disseminated ; more fre quently crystallised, and in the following figures : 1. Rectangular four-sided prism, in which the termi nal planes are set on obliquely, which is the fundamental figure*. 2. The preceding figure, in which the lateral edges are truncated. 3. N° 1. in which two opposite lateral edges are be velled. When these bevelling planes become of equal size with the original planes, an eight sided prism is formed; and when the original planes entire!»' disappear, there is formed 4. An oblique tour sided prism. .5. Rectangular four-sided prism bevelled on the ex tremities ; the bevelling planes set on the two opposite lateral edges; or obliquely bevelled on , the extremities, and the bevelling planes set on two opposite lateral planes. 6. Four-sided prism, obliquely acuminated with four planes, which are set on the lateral planes. Sometimes^ in the secondary figures, one or other of the lateral edges is truncated by an elongated trapezoi dal plane. The crystals are middle sized ; the surface of the crys tals is usually smooth, and sometimes longitudinally „ streaked. Externally it is splendent. Internally it is splendent on the foliated fracture ; but only shining on the uneven or conchoidal fractures, and is adamantine, inclining to tcsinous. The * The primitive fbrm, wording to Himy, is a rectangular -four-sided Prtim, jn which the terpiinal plants are set on obliquely.