Bob's Rock Shop: Phlogopite Plate(Site not responding. Last check: 2007-09-19)
Phlogopite is a member of the mica group that occurs in magnesium rich metamorphic rocks such as serpentinites, crystalline dolomites and altered peridotites.
Phlogopite crystals vary in color from yellowish to reddish brown to gray with a vitreous to submetallic luster, and sometimes exhibit a coppery appearance.
Phlogopite finds use as an industrial mineral, and plates of it have been historically used in applications that take advantage of this mica group mineral's properties as an electrical insulator.
As a general rule, spinels in the least differentiated rocks (phlogopite picrites) are chromite, and evolve, with magma differentiation, to Cr-, Al-poor and Fe3+-, Ti-rich spinel, by progressive and simultaneous increase in the magnetite and ulvöspinel contents.
The phlogopite population from Kendu is bimodal with respect to Ti-abundance and is Al-rich.
It is composed of approximately 50 vol% phlogopite and the mineralchemistry demonstrates that the tetraferriphlogopite trend, characteristic of Group 2 kimberlites, is absent while that of alnöite/minette is present.
The host rock is composed of phlogopite and clinopyroxene megacrysts set into a matrix of phlogopite, clinopyroxene, calcite, analcime, magnetite, and apatite.
Their blue colouration is due to intervalence charge transfer phenomena between Fe and Ti The purple colour of some Yogo sapphires is due to a small amount of Cr-content.
A phlogopite separate from the Yogo dike yielded a K-Ar date of 48.2 ± 1.3 Ma.
WATER, PHLOGOPITE, AMPHIBOLE, CARBONATITE AND A NEW MODEL FOR THE LITHOSPHERE/ASTHENOSPHERE AND THE LOW VELOCITY ZONE ...(Site not responding. Last check: 2007-09-19)
Clinopyroxene is the dominant phase; garnet, olivine, spinel, and orthopyroxene occur in variable amounts.
Minor phlogopite and amphibole, and melt pockets are also present.
Phlogopite occurs as veins and as discrete crystals that are sometimes associated with carbonates, which are interpreted to be carbonatitic melts.
Abstract - NH4-Phlogopite and ND4-Phlogopite(Site not responding. Last check: 2007-09-19)
Both phases are characterised via IR spectroscopy at 298 and 77 K and Rietveld refinement of their X-ray powder diffraction pattern.
Both the NH and ND molecules are found to occupy the interlayer site in the phlogopite structure.
Electron microprobe analyses indicate that both the NH - and ND -phlogopites deviate from the ideal phlogopite composition both with respect to variable Si/Al and Mg/Al on the tetrahedral and octahedral sites, respectively due to the "Tschermaks"-substitution.
The micamineralphlogopite, when it is cleaved, results in a rougher surface.
For one thing, there is no equivalent to the "grading" scheme as there is for the muscovite form of mica since that scheme is based on optical clarify (which phlogopite clearly does not have) and the presence (or absence) of iron oxide and other inclusions, which phlogopite seems to not have at all.
Thin flakes show a property known as asterism or a six pointed star when a light source is viewed through the crystal wihch is caused by the presence of inclusions.
The electrical properties of Muscovite, which is one of the best insulating materials, are superior to those of phlogopite, and in addition it is somewhat stronger mechanically and is harder and more flexible.
The Phlogopite is softer than Muscovite and has poorer electrical properties and electrical resistance.
Mica Paper board is a constituted muscovitemica paper, which impregnated, bonded with heat resisting silicone resin.
The behavior during dissolution of edge and basal surfaces of the micaphlogopite were examined using in situ atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS) and low-energy electron diffraction (LEED) in an attempt to characterize the reactive surface area during dissolution.
Long-term in situ AFM observations of phlogopite dissolution reveal that exposed (001) surfaces also display a distinct reactivity, though it operates on a different time scale.
Compositional characterization of the phlogopite after reaction shows that for pitted phlogopite surfaces, dissolution is characterized by leaching of octahedral cations and polymerization of the silica-enriched residual layer.
AN INTERFEROMETRY INVESTIGATION OF PHLOGOPITE DISSOLUTION: IMPLICATIONS FOR CRYSTAL DISSOLUTION WITHOUT THE FORMATION ...(Site not responding. Last check: 2007-09-19)
In the case of phlogopite, we know that the formation of etch pits at the (001) cleavage surface under acidic conditions is not common (e.g., Rufe and Hochella, 1999).
We have measured absolute dissolution rates in HCl (pH 3) of the (001) and (hk0) faces of a near endmember phlogopite with a vertical scanning interferometer at 25, 50, and 80° C. This technique allows direct observation of dissolution by quantifying surface normal retreat or advance of oriented phlogopite surfaces.
The changes in surface topography are measured relative to a reference surface, and do not require an external measurement or estimate of surface area.
