Moonstone. A nearly pellucid variety of feldspar, showing pearly or opaline reflections from within. The best specimens come from Ceylon. Their value is not much more than the expense of cutting.
“Let us urge forward our spirits, and make them approach the invisible world, and fix our mind upon immaterial things, till we clearly perceive that these are no dreams; nay, that all things are dreams and shadows besides them.”
–Henry Scougal, The Life of God in the Soul of Man