This video features the mineral, muscovite (using 360 degree photography). Muscovite is a very soft mineral, but relatively easy to identify. There is an obvious layering to muscovite (it forms thin sheets like pages in a book)--and it can split/cleave more easily between the individual layers, than through the individual layers. This preferential layering/orientation is called a cleavage. Muscovite is considered to have a good, or excellent, cleavage (actually if often splits so well along between the layers, that is called "perfect" cleavage).

Muscovite is transparent to translucent in thin sheets. Sometimes these sheets of mica can be about two meters across. It is used as common windows, before glass windows were available. However, because muscovite has a relatively high melting temperature, it is used as windows in older kitchen ovens, and as windows in smelters. But now muscovite is mostly used in electronics--as an electrical insulator. It is also ground up into tiny flakes as a sort of glitter material in make up and children's products (such as in children's pretty princess toothpaste). Muscovite also is a low-grade aluminum ore (over 40% aluminum).

Hello Rock People! This is Dave the Geology Dude. Identification notes are below in this text. Note that I have other videos that provide more rock identification information on my YouTube channel. It is best to try to see many examples of the same rock type--because only then you understand the range of variables that can be associated with each rock type. Don't forget that: Geology isn't rocket science--it's Rock Science! Please "like" and subscribe to this YouTube channel!

Identification information for this rock:
1) Environment: muscovite is found around a variety of igneous and metamorphic rocks--especially in granite, pegmatite, and schist
2) Shape and cleavages: muscovite is very similar to biotite. Both muscovite and biotite are in the mineral group called micas. The structure to micas are like tightly stacked thin sheets (or very thin layers--that are almost paper-thin)--like packs of paper stacked within within a common book. Micas usually can be split into individual or packs of sheets--by hand (often with the initial help of prying apart with your fingernails). Yes, you can break these rocks with only your fingers. These micas have cleavages--which is a distinct layering structure--that will preferentially split (or cleave) between this layering structure. Muscovite tends to split into sheets more easily than biotite, but biotite can split easily too. Note that the individual sheets of muscovite--after separating into individual sheets--often can be flexed or bent slightly, without damaging the sheet-like structure of the mineral. But it is possible to break through the individual sheets by hand--if you try to rip or fold the individual sheets
3) Color--muscovite is shiny transparent to translucent vaguely yellow/tan color. Although it may have some small areas with dull brownish colors
4) density--density is similar to most other rocks
5) hardness--it is only 1 on Mohs' hardness scale. It will not scratch glass (but may leave a powder or flakes on the glass, because the glass instead will be abrading the rock--as you try to scratch the glass with it. Your fingernail will scratch the surface of muscovite, and your fingernail has a hardness of about 2.5- to- 3.0
6) streak-- muscovite really does not leave a streak
6) acid reactivity: will not react to acid contact
7) luster--muscovite has a nonmetallic glassy (or vitreous) luster.
8) often confused with biotite--because both of these micas form flat sheets. But biotite is consistently dark black in color, and muscovite is either colorless, or a transparent or translucent light-gray or a faint tan or yellowish-gray in color
9) Summary: muscovite is a shiny transparent to translucent mineral--with a nonmetallic glassy luster. It is easily cut/scratched by the end of a fingernail. This mineral forms tightly packed sheets like in a Post-It Note pad (often called books). Similar to Post-It Note pads (sold in America), the strength along the individual sheets of muscovite, is much more stronger (harder to break) than the bonds between the individual sheets. That is why it is much more easier and predictable that sheets in a Post-It Note pad will separate cleanly from the pad (or book of sheets), than to break or tear within the individual sheets

Music (YouTube Audio Library): Running Out (by Patrick Patrikios)

Copyright by David Knoblach, 2022. All rights reserved

свернуть