Arseniate of Copper

This is a new variety from Cornwall, and has such an attracting effect that it naturally excites inquiry, although nearly related to some of my former figures. The base of the crowded hemispherical bundle being left in flat star-form radii, compared to the most unusual appearance of Zeolite, it has thus by some got the appellation of Zeolite Copper, which rather tends to mislead; it perhaps has a better title to the name Hydrargillite Copper, from the nature of these radii, and also for the first appearance of the termination of the crystals, which, however, differ somewhat, being nearly related to tab. 303, being a modification of that appearance, but too indistinct to be made out. Some of the radii proceed immediately from a centre, while others are, as it were, formed on the outside of smaller hemispheres. See the right hand side of the upper figure. These specimens exhibit a remarkable variety of colour from the dark green aspect of the crowded shining radii, and the lighter more separated and somewhat opaque vivid blue green radii mingled among them. The ground between is covered with a nearly powdery vivid green Carbonate of Copper, besides a byssus-like brownish Arseniate of Copper, but not very conspicuous; it is upon Quartz with Mica, &c. The upper specimen is in possession of Lady Aylesford. The lower one is on a fragment of nearly pure Quartz, in some parts a little ochry.