—, optical structure of, ix, 384.
—, specific gravities of various, Breithaupt, xxxi, 268.
—, Hosack's donation of, iv, 396.
—, pseudomorphous, account of, xlviii, 66, 81.
— of trap, origin of, J. D. Dana, xlix, 49.
— of volcanic rocks, iv, 212, 215.
—, zeolitic, not formed at the formation of the containing rock, J. D. Dana, xlv, 116, 145.
—, —, rendered hydrous bysteam of eruption, H. D. Rogers, xlv, 147.
—, in London, prices of, v, 169.
— of Europe, value of, xxix, 368.