The Collaborative International Dictionary
Sphalerite \Sphal"er*ite\, n. [Gr. ??? slippery, uncertain. See Blende.] (Min.) Zinc sulphide; -- called also blende, black-jack, false galena, etc. See Blende (a) .
Blende \Blende\, n. [G., fr. blenden to blind, dazzle, deceive, fr. blind blind. So called either in allusion to its dazzling luster; or (Dana) because, though often resembling galena, it yields no lead. Cf. Sphalerite.] (Min.)
A mineral, called also sphalerite, and by miners mock lead, false galena, and black-jack. It is a zinc sulphide, but often contains some iron. Its color is usually yellow, brown, or black, and its luster resinous.
A general term for some minerals, chiefly metallic sulphides which have a somewhat brilliant but nonmetallic luster.
Wiktionary
n. 1 (context obsolete mineral UK English) sphalerite; zincblende. 2 (context obsolete English) caramel or burnt sugar, used to colour wines, spirits, ground coffee, etc. 3 (context obsolete English) A large leather vessel for beer, etc. 4 (context obsolete English) The (taxlink Quercus nigra species noshow=1), or (vern barren oak pedia=1).
Usage examples of "black-jack".
In some of the gardens there were brave and defiant shows of bright blooms, barbeton daisies, carinas and flaming red poinsettia, but in most of them the bare untended earth, patched with black-jack and khaki-bush, told of the tenants indifference.