millerite

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A nickel sulfide mineral, NiS, usually occurring in long hairlike crystals and sometimes used as a nickel ore.

from The Century Dictionary.

• noun A disciple of the American William Miller, who from 1833 till his death in 1849 publicly interpreted the Scriptures as fixing the second advent of Christ and the beginning of the millennium in the immediate future (at first about 1843). His followers form a still existing denomination of Adventists.
• noun Native nickel sulphid, a mineral having a bronze color and metallic luster, often occurring in tufts of capillary crystals, and hence called hair-pyrites, capillary pyrites.

from the GNU version of the Collaborative International Dictionary of English.

• noun A believer in the doctrine of William Miller (d. 1849), who taught that the end of the world and the second coming of Christ were at hand.
• noun (Min.) A sulphide of nickel, commonly occurring in delicate capillary crystals, also in incrustations of a bronze yellow; -- sometimes called hair pyrites.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun geology A nickel sulfide mineral, NiS, that occurs as hairlike tufts

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a yellow mineral consisting of nickel sulfide; a minor source of nickel