Opal. A mineral consisting, like quartz, of silica, but inferior to quartz in hardness and specific gravity. The precious opal shows a peculiar play of colors of delicate tints and is highly esteemed as a gem. One kind, with a varied play of color in a reddish ground, is called harlequin opal. The fire opal (which comes from Mexico) has colors like the red and yellow of flame.

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“When the soul is once taken up with the things that are of absolute necessity, it will not be much troubled about other things.”
–Jeremiah Burroughs, The Rare Jewel of Christian Contentment