vitrain

vitrain (countable and uncountable, plural vitrains)

1. A constituent of banded bituminous coal consisting of a horizontal glossy band of friable material.
   • 1996, T.S. Golosinski, Guo Yuguang, Mining Science and Technology 1996, →ISBN, page 396:

     The caking behaviour of vitrain and clarain could be improved after the coal has been picked out.

   • 1997, Yang Qi, Geology of Fossil Fuels: Coal, →ISBN, page 149:

     In order to measure relatively accurately the activation energy of coal, and to exclude the disturbance from coal samples, the hand-picked banded vitrains in bright coal are adopted as experimental samples (Table 1).

   • 2012, C.E. Snape, Composition, Geochemistry and Conversion of Oil Shales, →ISBN, page 491:

     Thus, it may be concluded that a lower viscosity of plastic vitrain grains facilitates pores to grow and coalesce and grains to stick to one another to create intergrain pores.

• fusain

• antivir