CROSS-STONE. 32 5 smoke-grey; and the yellowish-white into cream-yellow, brick-red, and flesh-red. It occurs very rarely massive ; most frequently crys tallised, in the following figures : 1. Generally in broad, seldom in equilateral, rectan gular four-sided prisms, rather acutely acumi nated on the extremities with four planes, which are set on the lateral edges, fig. 84 *. 2. The preceding figure, in which the edges formed by the meeting of the acuminating planes that rest on the broader lateral planes are truncated, fig. 85 f. When these acuminating planes be- • < come so large that the original acuminating planes almost disappear, then the prism appears bevel led on the terminal planes. Very rarely No. 1. becomes very low, when 3. A kind of srarnet dodecahedron is formed. 4. Twin crystal, which is formed by two crystals of Np. 1. intersecting each other, in such a manner that a common axis and acumination is formed, and the broader lateral planes make four re-en tering right angles, fig. 8fi j. The crystals are small, middle-sized, and very small, an d ar e singly superimposed. I he surface of the smaller lateral planes is double plu- mosely streaked, the broader lateral planes transversely streaked, and the acuminating planes streaked parallel w ith the smaller lateral planes. X 3 Internally * Harmotomc dodecaedre, Hauy. t Harn*tome partiel, Hauy. t Harmttomc cruciformc, Hauy. The primitive form, according to Hauy, is an octahedron, with iaosceles triangular f ucts>
