an old term in Natural History, applied to some fossils, of the class of gypsums, the characters of which are, that they are of a soft texture, and of a dull opaque look, being composed, as are all the other gypsums, of irregularly arranged flat particles. The word is derived from the Greek \(\chi\) \(\alpha\) \(\lambda\) \(\sigma\) \(\mu\) \(\iota\) \(\mu\) \(\iota\) \(\sigma\), a fragrant or small particle; from the flaky small particles of which these bodies are composed. Of this genus there is only one known species. This is of a tolerably regular and even structure; though very coarse and harsh to the touch. It is of a very lively and beautiful red colour; and is found in thick roundish masses, which, when broken, are to be seen composed of irregular arrangements of flat particles, and emulate a striated texture. It will neither give fire with steel nor ferment with acids; but calcines very freely and easily, and affords a very valuable plaster of Paris, as do all the purer gypsums. It is common in Italy, and is greatly esteemed there; it is also found in some parts of England, particularly Derbyshire; but there it is not much regarded.