However, marshallite can easily be processed by elutriation, air elutriation, and chemical processing with extraction of monomineralic
fractions and a simultaneous decrease in [Fe.sub.2][O.sub.3] to a tenth of a percent.
Fifteen dolomite samples and five calcite samples were obtained for C-O isotopic analysis following the selection of monomineralic
rocks from the 17 dolomite or limestone samples that were acquired for this study.
The Digdeguash-Flume Ridge transition on the eastern flank of the Fredericton trough is marked by four significant changes: a rapid shift from non-calcareous to at least slightly calcareous sandstone; a decrease in grain size of the coarsest beds from granules and coarse sand to fine sand and silt; a sharp decrease in the amount of pelite (aluminous slate in D and E horizons of Digdeguash Bouma sequences is replaced by quartzofeldspathic siltstone in the Flume Ridge); and an increase in clast maturity of the coarse fraction, with typical sand-to granule-sized lithic fragments in the Digdeguash mostly giving way to monomineralic
quartz and feldspar grains in the Flume Ridge.
character of each grain is proven by its electron diffraction pattern, checking the existence of a single network and, therefore, a single crystalline phase.
The most efficient separation techniques operate on monomineralic
particles obtained after crushing and grinding, but obviously this ideal situation can hardly be achieved and most often multiphasic or so-called unliberated particles are present in the process.
The celestine geodes are virtually monomineralic
; unlike well-known celestine deposits in the U.S., France, Italy (Sicily), Germany and Poland, there is no associated hydrothermal calcite, aragonite, barite, quartz, sulfur or gypsum.
The highest grade, nearly monomineralic
brucite deposits are found in aureoles where the protolith consists of magnesite with little or no calcite, clays, chert or other mineral impurities.
) quartz grains accounted for more than half of the identifiable inclusions.
Although the thermal conductivity in monomineralic
systems is mainly controlled by porosity and the thermal conductivity of pore fluid, the exact mathematical function between these two parameters is not self-evident due to variations in pore structure, microfracturing, and degree of saturation.
Most of the metacarbonate rocks are monomineralic
(calcite or dolomite) but locally contain talc, muscovite, phlogopite, garnet, and minor tremolite.