Idocrase. A mineral occurring in tetragonal crystals and also massive, of a brown to green color, rarely sulphur yellow or blue. It is a silicate of alumina and lime, with some iron and magnesia. It is common at Mt. Vesuvius.
“Every comfort that the saints have in this world is a promise to them of those eternal mercies which the Lord hath provided for them: as every affliction that the wicked have here, is but the beginning of sorrows.”
–Jeremiah Burroughs, The Rare Jewel of Christian Contentment