Also found in: Wikipedia.
Related to K-feldspar: plagioclase, Potassium feldspar


 (kā′fĕld′spär′, -fĕl′-)
Mentioned in ?
References in periodicals archive ?
Appearance and soundness ofpyterlite Pyterlite is a porphyritic rapakivi granite variety with rounded, densely dispersed K-feldspar megacrysts 2-3 cm in diameter.
K-feldspar and hydrothermal biotite forming potassic zones in both diorite and quartz monzodiorite, commonly accompanied by quartz veining, intense pervasive epidote alteration, and widespread sericite
Of these recipes the standard glaze (STG) and those with the wastes added as 20 percent (G1) replacing Na-Feldspar, 20 percent (G2) replacing K-Feldspar, 30 percent (G3) replacing ulexite, 40 percent (G4) replacing Na-and K-feldspar, 70 percent (G5) replacing Na-Feldspar, K-Feldspar and ulexite in the starting batch were reported hereby (Table II).
Gold mineralization at Windfall Hills is associated with quartz stock-works and alteration zones of silica, pyrite, K-feldspar, sericite and clay.
Extensive hydrothermal alteration in the form of silicification, carbonate, hematite/magnetite and K-feldspar veins was observed in the drill cuttings.
Crystals are small (<3 mm maximum diameter) and include rounded embayed quartz, subhedral K-feldspar (anorthoclase, based on the presence of fine-scale cross-hatch twinning), and subhedral plagioclase set in a locally spherulitic groundmass of cryptocrystalline quartz and feldspar.
Vermiform kaolinite also occurs as a result of k-feldspar alteration.
Ratios of plagioclase to K-feldspar may vary systematically between and within moraines but needs to be confirmed by more extensive analysis.
2) were calcite, dolomite, quartz, K-feldspar and clay minerals (mostly illite), which are typical constituents of oil shale mineral matter and were preserved or slightly changed during the retorting process.
Aluminium oxide has entered mainly clay minerals, titanium oxide reflects titanium minerals, and potassium oxide has entered both clay minerals and K-feldspar in these rocks.