Since my communication on this subject published in the first number of the Mineralogical Magazine, I have made further observations, and have found other specimens greatly varying, but all embodying the same general principle of solid quartz enclosing the oxides of iron. The quartz is perfectly solid, breaking with its usual eonchoidal fracture, and though richly colored with the oxides of iron disseminated through it in beautiful forms, is itself transparent, so that the forms and colors of

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... e iron are well seen. The colors are various shades of red, yellow, amber, grey, &c., and [hose colors are distributed in well-defined forms, and not in mere tints as in the case of amethyst, &c.