Also 8 elvin. [In the West Cornwall Gloss. (E. D. S.) referred to Corn. elven spark, ‘the rock being so hard as to strike fire.’]
1. The name given in Cornwall to intrusive rocks of igneous origin, so hard as to resist the pick, as quartz-porphyry, whinstone, etc. Also attrib.
1791. Beddoes, in Phil. Trans., LXXXI. 65. Whether the basaltes proceeds southward by such interruptions till it join the Elvin or Whinstone.
1864. Lyell, in Reader, 17 Sept., 358. One wall consisting of elvan or porphyritic granite.
1865. J. T. F. Turner, Slate Quarries, 22. Elvan (or slate whose cleavage was destroyed by internal heat) of unknown thickness.
1879. Rutley, Stud. Rocks, iv. 33. The quartz-porphyries or elvans.
2. A broad vein or dike of this rock.
1849. Murchison, Siluria, xvii. 417. Limestone pierced by elvans, or granite dykes.
Hence Elvanite. Min. = ELVAN. Elvanitic a., containing or characterized by elvanite.
1882. Geikie, Text-bk. Geol., II. II. § 6. 136. Elvan or elvanite is a Cornish term for a crystalline-granular mixture of quartz and orthoclase.
1883. Times, 26 July, 13/4. Granulite is an elvanitic or fine grained granite.
