A rather common type is illustrated in figure 1, plate 39, which was drawn from a doubly terminated crystal free from the matrix and 42 mm. long by 8 mm. wide. The slight curvature in g is not shown. This illustrates about the average proportional length of the prisms. It is very common for the front planes to be rather small and the back planes to cut much farther down on the prism. The width of g is very variable and the planes p are frequently the largest of the terminal planes.

Figure 2 is from a stout prism some 12 mm. wide and shows a high development of the unit pyramids. The g faces are narrow and the "edges" g ^p curved and of varying distance from the o ^ g edges.

Figure 3 shows a peculiar asymmetric development and was drawn from a doubly terminated prism 8 mm. long by 3 mm. wide, though only the planes at one termination are shown. It illustrates the usual ways in which r (221) appears, either as a small triangular face between g and the prisms, or less commonly as a rhomboidal form bounded by the prisms, and by o and p when g is narrow or absent.

Only one crystal of the type shown in figure 4 was found. It shows the front faces s (111) largely developed and cutting down much farther on the prisms than the back faces. Both i (112) and g are absent, and r and p occur as narrow strips bordering o.

Hardness between 5 and 6. Density 3.18-3.19. Cleavage perfect, prismatic parallel to m (110), with normal angle of 80° 18².

The crystals are black and lustrous; in thin sheets or splinters, deep blood red. Cleavage plates show strong pleochroism: c deep ocreous yellow to brownish red; a pale yellow to reddish yellow in thicker sections; c ¹ ^c= 14º5.

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