vitrainn.

1919 M. C. Stopes in Proc. Royal Soc. B. 90 472 These four distinguishable ingredients, all of which..are to be found in most ordinary bituminous coals, I name provisionally as follows:—(i) Fusain. (ii) Durain. (iii) Clarain. (iv) Vitrain. Together the equivalent of ‘bright’ or glance coal of various authors.

1930 Engineering 18 July 92/1 Vitrain and durain belonged to the former [coking coal] and fusain to the latter [non-coking coal] class.

1975 D. G. Murchison et al. tr. E. Stach Textbk. Coal Petrol. v. 334 The first step..is the crushing of the run-of-mine coal... When a seam contains thick layers of bright coal, the soft and mostly brittle vitrain concentrates in the smalls, below 10 mm.