from The Century Dictionary.
- noun A brownishblack mineral consisting mainly of niobic acid and yttria, and crystallizing in the tetragonal system.
from the GNU version of the Collaborative International Dictionary of English.
- noun (Min.) A mineral of a brownish black color, essentially a tantalo-niobate of yttrium, erbium, and cerium; -- so called after Robert Ferguson.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun A
mineralcomposed of oxides of various rare earth elements.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- noun a dark mineral consisting of oxides of yttrium and erbium and tantalum and other minerals
from Wiktionary, Creative Commons Attribution/Share-Alike License
Fourth, about four litres of helium were prepared from fergusonite; and this gas was fractionally diffused during about three months, in the hope of obtaining heavier fractions, which might contain the looked-for gases; for they would certainly betray themselves by their spectra, if present.
It is important to realize that the tantalum, niobium and zirconium production does not involve significant extra costs as they occur in the same mineral phases that contain the heavy rare earths (zircon and fergusonite).
By contrast, Dotson Ridge is characterized by steeply dipping pegmatitic and aplitic dikes variably mineralized with REE minerals including kainosite, xenotime, allanite, bastnaesite, thalenite, synchisite, and fergusonite.