THE MINERAL POLYLITHIONITE
Polylithionite, which is named from the Greek for having much lithium
, is not a well know mineral.
Yet it is an attractive mineral that is available on the mineral markets.
The best specimens arguably come from the famous quarry at
Specimens there are found mostly in the altered and unaltered pegmatites with other rare minerals.
Polylithionite is found at other alkaline rich pegmatitic deposits such as the
Ilimaussaq alkaline complex in Greenland and at Langesundsfjord, Norway.
lemon yellow and this makes distinguishing it from most other micas rather easy.
Its habit to form rosettes is distinctive as well.
Any yellow to silvery white, fluorescent mica like crystals attached to specimens of other Mont Saint-Hilaire specimens are probably polylithionite.
Polylithionite is certainly not one of the more well know mica minerals.
It is a true mica closely related to other lithium rich micas;
Polylithionite, like other micas, has a layered structure of lithium aluminum silicate sheets weakly bonded together by layers of potassium ions.
These potassium ion layers produce the perfect cleavage.
Polylithionite's rarity, associations with other rare minerals, attractive color and fluorescent color and crystal habit make it an ideal collection mineral.
- Color is colorless, white, bluish, greenish, yellow, brown, pink, silvery to pearly white.
- Luster is pearly to waxy.
- Transparency crystals are transparent to translucent.
- Crystal System is monoclinic; 2/m
- Crystal Habits include pseudohexagonal tabular to platy crystals forming "books" and rosettes.
- Cleavage is perfect in one direction producing thin sheets or flakes.
- Fracture is not readily observed due to cleavage but is uneven.
- Hardness is 2 - 3.
- Specific Gravity is approximately 2.6 - 2.8 (average)
- Streak is white.
- Other Characteristics: Specimens are
fluorecent lemon yellow under shortwave UV light.
- Associated Minerals are many and include
- Notable Occurrences include the type locality of Kangerdluarsuk, Ilimaussaq
alkaline complex, Greenland as well as Langesundsfjord, Norway; Varutrask, Sweden; Washington Pass, Okanogan County, Washington; Landsman Camp, Graham County, Arizona and
Point of Rocks, New Mexico, USA; Dara-i-Poiz Massif, Tadzhikistan and of course
Mont Saint-Hilaire, Quebec, Canada.
- Best Field Indicators are crystal habit, fluorescence, color, cleavage, locality and associations.