Min. Forms: α. 8 feldspat(h, feltspat. β. 8 fieldspar, 8– feldspar. γ. 8–9 felspar. [The forms feldspat(h, feltspat are adoptions (the latter through Sw.) of Ger. feldspat(h, f. feld FIELD + spat(h spar. Almost contemporaneously appear the wholly or partially translated forms field-, feldspar. The corrupt spelling felspar was introduced by Kirwan on the ground of a supposed derivation from fels, and is still more common than the correct form.]
A name given to a group of minerals, usually white or flesh-red in color, occurring in crystals or in crystalline masses. They consist of a silicate of alumina with soda, potash, lime, etc.
1757. E. M. Costa, Nat. Hist. Fossils, 287. The opaque quartz or feldspath.
1772. trans. Cronstedt’s Min., App. 8. If the characters of this field-spar are accurately examined.
1776. G. Edwards, Fossilology, 54. A black felt-spat … found in Sweden.
1784. Kirwan, Elem. Min., 102. Sandstone mixed with mica and feltspar.
1785. J. Hutton, Th. Earth, in Trans. R. Soc. Edin., I. 229. Strata consolidated by feldspar.
1792. Phil. Trans., LXXXII. 30. D. Hoffman discovered that red blende and feldspat were luminous when pieces of either were rubbed together.
1794. Kirwan, Min., I. 317, note. This name seems to me derived from fels, a rock … hence I write it thus, felspar.
1835. Sir J. Ross, Narr. 2nd Voy., xxix. 406. The coast was formed of granite, containing large crystals of felspar, with garnets.
1860. Maury, Phys. Geog. Sea, x. § 494. 272. Granite is generally composed of feldspar, mica, and quartz.
attrib. 1810. T. Thomson, A System of Chemistry (ed. 4), II. 551. The felspar glaze does not melt at the heat requisite for fusing the colours and their flux.
1830. Lyell, Princ. Geol., I. 263. Traversed in all directions by veins of felspar porphyry.
1862. Dana, Man. Geol., § 85. 80. Feldspar-Euphotide … consisting of a minutely-granular feldspathic base with disseminated diallage or smaragdite.
1872. W. S. Symonds, Rec. Rocks, iv. 113. Criccieth Castle stands on a felspar rock.
Hence Feldsparic a, resembling feldspar; = FELDSPATHIC. Feldsparite = FELDSPAR. Feldsparry a., containing feldspar.
1811. Pinkerton, Petral., I. 157. Hardness, of course felsparic.
1832. Boase, Geol. Cornwall, 211. Felsparite or Felspar-Rock.
1852. Th. Ross, trans. Humboldt’s Trav., I. ii. 98–9. The feldsparry lavas of the Peak, of a much less black tinge than those of Arso in the island of Ischia, whiten at the edge of the crater from the effect of the acid vapours; but internally they are not found to be colourless like that of the feldsparry lavas of the Solfatara at Naples, which perfectly resemble the trappean porphyries at the foot of Chimborazo.
