. Annals of Philosophy. 98 Mr. W. Phillips on Skorodite. [Feb. from a mine in the neighbourhood of St. Austell," in Cornwall. By the gentleman who transmitted them, they are imagined to be a variety of the arseniate of iron ; but he laments that their scarcity had prevented his ascertaining their composition, and requests the insertion of a notice respecting them in the Annals of Philosophy. The largest of these crystals does not exceed in size the head of an ordinary pin, but many of them are so complete as to leave it a matter of doubt whether they ever were attached to a matrix ; a few
. Annals of Philosophy. 98 Mr. W. Phillips on Skorodite. [Feb. from a mine in the neighbourhood of St. Austell," in Cornwall. By the gentleman who transmitted them, they are imagined to be a variety of the arseniate of iron ; but he laments that their scarcity had prevented his ascertaining their composition, and requests the insertion of a notice respecting them in the Annals of Philosophy. The largest of these crystals does not exceed in size the head of an ordinary pin, but many of them are so complete as to leave it a matter of doubt whether they ever were attached to a matrix ; a few, however, are deposited on some small fragments of quartz. In form they very closely resemble that of the skoro- dite, given in the third edition of my Elementary Introduction to Mineralogy ; the planes rfe and d>', are, however, wanting in the second of the following figures, which represents the form of the crystals lately received from Cornwall; while almost every one of them exhibits the planes c c, which are not observable in the crystals of the skorodite, or in those of the martial arseniate of copper. Externally these crystals are of the dark bottle-green colour, very common to some of the prismatic varieties of the arseniate of cop- per ; but this is not in fact the true colour of the substance itself, which, on holding the crystals, or thin fragments of them between the eye and the light, is found by the assistance of a glass to be of the pale blue, so common to the mar- tial arseniate of copper. The dark-green colour arises from the mechanical intermixture of a multitude of very minute specks, of that colour, visible on the surface, and also by transmitted light. M on M 120° MonA 119 Mondi 141 d\ on dv 103 d\ ondi" 112 c on h 154 The first figure represents a right rhombic prism, the primary form of the martial arseniate of copper, the skorodite, and also of the crystals which form the subject of this notice: the planes d\, d\, of the latter, generally prese
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