Cubical Red Oxide of Copper

Good cubical crystallizations of Red Oxide of Copper are much rarer than octaëdrons: see tab. 53.

This specimen came from near Redruth in Cornwall. It is crystallized in distinct cubes sometimes, but oftener in rather irregular groups, yet with their edges and planes parallel to each other, seldom like Fluor, tab. 73, or Galæna, tab. 24, &c., which are generally more confused. It rarely forms large cubes, although I understand that some have been found a quarter of an inch in diameter. They are often truncated at their solid angles, forming the cubo-octaëdre of Haüy, t. 63 and 71. The magnified figure represents a group somewhat like one on the specimen, which has a large cubo-octaëdre at the left hand corner, and the rest consists of various sized cubes, and one or two of another group, showing that the different groups may stand in different directions.

These are generally more of a beautiful Bohemian or Scotch garnet^* colour than the octaëdrons. We know of no difference in their substances.