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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“Prayer and thanks are like the double motion of the lungs, the air that is sucked in by prayer is breathed forth again by thanks.”
–Thomas Goodwin, The Return of Prayers