feld·spar (fĕldspär′, fĕl-) also fel·spar (fĕl-)
Any of a group of abundant rock-forming minerals occurring in igneous, metamorphic, and sedimentary rocks, and consisting of silicates of aluminum with potassium, sodium, calcium, and, rarely barium. About 60 percent of the earth's outer crust is composed of feldspar.
[Partial translation of obsolete German Feldspath : Feld, field (from Middle High German veld, from Old High German feld; see pelə-2 in the Appendix of Indo-European roots) + Spath, spar.]
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