| Appearance: | Pale brown to brown, vitreous to pearly luster, transparent to translucent |
| Chemical formula: | K Mg3 AlSi3 O10 (OH)2 |
| Chemical name: | Potassium magnesium aluminum silicate hydroxide |
| CAS #: | 12001-26-2 |
| Crystal system: | Monoclinic, 2/m |
| Cleavage: | Perfect in one direction producing thin sheets or flakes |
| Fracture: | Not generally observed because of the cleavage properties |
| Specific gravity: | 2.9+ |
Generally speaking, the kinds of people who use muscovite mica substrates (and look at them with microscopy)
want very smooth surfaces. The mica mineral phlogopite, when it is cleaved, results in a rougher surface.
The mineral also lacks the high optical clarify of muscovite, at least when talking about grades V-4 or better.
But there are some significant differences between the more familiar (to most) muscovite form of mica vs. the
less familiar phlogopite form of mica.
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. So while there are some differences
in what one might call "quality", such differences have to be characterized and measured via a scheme entirely
different than the one used for the characterization and grading of muscovite mica (e.g. V-1, V-2, etc.).
Some researchers would express a preference for phlogopite because they want to benefit from its higher
melting point (~1800°C vs. ~ 1600°C for muscovite). Yet others might want a substrate that is free
of iron oxide impurities but at a lower price than the top grades of muscovite (e.g. V-1 and V-2).
Another group of users prefer phlogopite because the cleaved surface, being rougher, contains more surface
area and this could be important where issues of adhesion are involved.
When cleaved, the sheets are flexible and elastic, and can be bent and will flex back elastically
to their original flatness. Thin flakes show a property known as asterism or a six pointed star when a
light source is viewed through the crystal which is caused by the presence of inclusions.
SPI Supplies can supply phlogopite in just about any size or shape, just as we can do for muscovite mica. The cost
of the raw material is not substantially different than it is for muscovite. But whereas with muscovite we benefit
from very large purchases, large conversion runs where the larger pieces are die cut down to smaller pieces, etc.,
for this less common form of mica, at least in the scientific laboratory, the runs will be much shorter and the
start up costs will necessarily be spread out over a smaller number of units.
Packaging: 100 Pieces per Pack
To Ask a Question or Make a Comment