CHYSOMELA, a genus of insects belonging to the order of coleoptera. See Entomology Index.

CHYSOPHYLLUM or BULLY-TREE. See Botany Index.

CHYSOPLENUM. See Botany Index.

CHYSOPRASUS, or CHYSOPRASIS, the 10th of the precious stones mentioned in the Revelation, as forming the foundation of the heavenly Jerusalem. The chrysoprasus is by mineralogists reckoned to be a variety of the chryslite, and by Cronstedt called the yellowish green and cloudy topaz. He conjectures that it may perhaps be the substance which serves as a matrix to the chryslite; as those that he had seen were like the clear-veined quartz, called in Sweden milk crystal, which is the first degree of crystallization.

The chrysoprasus, according to M. Magellan, is of a green colour, deeper than the chryslite, but with a yellowish tinge inclining to blue like the green leek. M. Achard says that it is never found crystallized, chryson, and that it is semi-transparent. By others it is reckoned among the quartz, and its colour is supposed to be owing to the mixture of cobalt, as it gives a fine blue glass when melted with borax, or with fixed alkali. M. Achard, however, found the glass of a deep yellow when the fusion was made with borax; and that it really contains some calx of copper instead of cobalt. M. Dutens says, that some gold has been found in this kind of stone; but this last belongs in all probability, says M. Magellan, to another class of substances, viz. the vitreous spars.

To the latter belongs most probably the aventurine, whose colour is generally a yellow brown red; though sometimes it inclines more to the yellow, or greenish, than to the red. These stones are not quite transparent: some indeed shine with such a brilliancy, as to render them of considerable value, but they are very rare. The common aventurine is but an artificial glass of various colours, with which powder of gold has been mixed; and these imitated aventurines so frequently excel the native ones in splendour, that the esteem of the latter is now much lowered. With regard to the chrysoprasus, its name, from πράσινος, shows it to be of a greenish blue colour, like the leaves of a leek; it only differs from the chryslite in its bluish hue.