Minerals & Gemstone 480x104
Minerals & Gemstone 480x104
Minerals V2 banner 160x600



Advertising Information

Bronze Phlogopite

The Mineral phlogopite




Phlogopite is a common form of mica, and it is usually distinguished by its brownish-red color. Phlogopite, like the other important mica's, can come in very large crystal sheets. Thin sheets can be peeled off as layers, and thin layers maintain an interesting metallic-looking transparency.

Biotite, another common mica, is recognized by the IMA as a mineral group of related micas rather then as an individual mineral type. Phlogopite is one of the member minerals of the Biotite group, and is chemically and structurally similar to the other Biotite minerals. It represents the magnesium rich end member of the Biotite group, whereas the other forms of Biotite are rich in iron.

Phlogopite contains three closely related minerals (some consider these as varieties):
- Tetraferriphlogopite: KMg3(Fe3+Si3O10)(OH)2
- Shirozulite: KMn3(AlSi3O10)(OH,F)2
- Fluorophlogopite: KMg3(AlSi3O10)F2

Phlogopite is very hard to clean because if washed it will absorb water internally and start to break apart. The best way to wash Phlogopite and other micas is with a dry electric toothbrush.
Chemical Formula KMg3(AlSi3O10)(OH,F)2
Composition Basic potassium magnesium aluminum silicate, sometimes with some iron and fluorine
Variable Formula K(Mg,Fe)3(AlSi3O10)(OH,F)2
Color Brown, reddish-brown, yellow-brown, yellow, gray, green, reddish-black
Streak Colorless
Hardness 2 - 3
Crystal System Monoclinic
3D Crystal Atlas
(Click for animated model) 
Crystal Forms
and Aggregates
Crystals are in thick flakes, micaceous masses and groupings, and in tabular, foliated, flaky, and scaly forms. Crystals may also be elongated with one dimension flat, or stubby triangular or hexagonally shaped crystals. Also forms in prismatic barrel-shaped crystals composed of dense parallel plates, and rounded nodules of dense crystals.
Transparency Translucent. Transparent in thin sheets.
Specific Gravity 2.8 - 2.9
Luster Pearly
Cleavage 1,1
Fracture Uneven
Tenacity Sectile, Elastic
Other ID Marks May fluoresce cream-white to light yellow.
In Group Silicates; Phyllosilicates; Mica Group
Striking Features Flaky habit, crystals, sectility, and mode of occurence.
Environment In marble formed from metamorphosed limestone and dolomite.
Rock Type Metamorphic
Popularity (1-4) 3
Prevalence (1-3) 1
Demand (1-3) 2


Phlogopite ON EBAY



USES
Phlogopite, being a poor conductor of heat and electricity, is used as an insulator for various electrical products. It is also used in the manufacture of spark plugs.

NOTEWORTHY LOCALITIES
Exceptional gemmy hexagonally shaped Phlogopite barrels come from Sar-e-Sang, Kokcha Valley, Badakhshan Province, Afghanistan. Enormous crystals come from Betroka, Tulear Province, Madagascar. Other well know localities are Mogok, Burma (Myanmar); the Yaogangxian Mine, Hunan Province, China; Pargas, Finland; and Monte Somma, Vesuvius, Italy. Interesting rounded Phlogopite spheres come from Hermanov, Czech Republic.

In the U.S., the best examples come from Franklin, Sussex Co., New Jersey. Other Phlogopite locations in the Franklin marble belt are the Lime Crest Quarry, Sparta, Sussex Co., New Jersey; and Amity, Orange Co., New York. Very large crystals come Pierrepont, St Lawrence Co., New York; and from Canada at South Burgess, Ontario.

COMMON MINERAL ASSOCIATIONS
Calcite, Diopside Chondrodite, Apatite, Graphite, Rutile

DISTINGUISHING SIMILAR MINERALS
Muscovite, Biotite - Can be hard to tell apart, although typical Phlogopite color is a different color then Muscovite and Biotite, and these are also not common in metamorphasized marbles where Phlogopite is found.


phlogopite PHOTOS
 
ADDITIONAL RESOURCES
 
DISCUSSIONView Forum | Post to Forum
Have a question about Phlogopite? Visit our Q&A Community and ask the experts!
PAGE SPONSOR  

To sponsor this page, click here.

Let us know how we can update this page
(Click for more details)
We strive for accurate content and locality information. If you feel any of the content is incorrect, or if you feel we are missing vital locality information, please fill out the form below so we can update the site. If you are requesting a locality be added, please only include significant locality occurences for the mineral.