Lepidolite Information about the mineral specimen, gem or Crystal

PHYSICAL PROPERTIES:
Chemistry: KLi2Al(Al, Si)3O10(F, OH)2
Composition: Potassium lithium aluminum
silicate hydroxide fluoride
Class: Silicates
Subclass: Phyllosilicates
Group: Mica
Crystal system: monoclinic
Fracture: uneven
Hardness: 2.5
Specific gravity: 2.8
Luster: vitreous to pearly
Streak: white
Cleavage: perfect in one direction
Color: violet to pale pink or white and rarely, gray-green to pale yellow.
Transparency: crystals are transparent to translucent.
Associated Minerals: quartz, feldspars, spodumene, ambygonite and tourmaline especially elbaite.

COMPOSITION:
Hydrous fluosilicate of lithium, potassium, and aluminum (about 5% Li2O, 12% K20, 26%
Al203, 51% Si02, 1.5% H20, and 4.5% F)

DISTINGUISHING CHARACTERISTICS:
Lepidolite was an uncommon mica but in recent years Brazilian finds have made it much more available on the mineral market. Lepidolite, 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. The typical violet to pink color of Lepidolite is characteristic and is the only field test available to identify Lepidolite from other micas. Pink muscovite or very pale Lepidolite may confuse an identification. Since Lepidolite colors can be confusing, a melting and flame test is desirable if there is any reason - such as the presence of colored tourmalines or of other lithium minerals for suspecting a mica to he Lepidolite, rather than the commoner muscovite. The fluorescence and flame tests will also distinguish some of the more intensely colored chromium chiorites, dumortierite, and similar hydrous silicates.

ENVIRONMENT:
Lepidolite is a mica mineral of lithium bearing pegmatite's. It is relatively rare, since it is only found in pegmatite's that show a long series of replacements by successive elements, and is always an associate of lithium minerals.

CRYSTAL DESCRIPTION:
Lepidolite crystals accompany other lithium bearing minerals such as tourmaline, amblygonite and spodumene. Lepidolite crystals can add character and value of these specimens. Crystals can be tabular or prismatic crystals with a prominent pinacoid termination. Lepidolite's four prism faces and two pinacoid faces form pseudo-hexagonal crystal "books". Well developed crystals with a Sharp hexagonal outline are rare. The sides of the crystal often tend to taper. Sometimes borders ordinary muscovite mica, but the cleavage flakes are not quite continuous. Commonly occurs in medium to fine-grained aggregates; One- to two-inch crystals, tapering down to a slender point and more prismatic than tabular, occur at some localities.

TESTS:
Fuses easily to a bubbly Fluorescent glass (blue and pinkish fluorescence). Colors the flame red.

LOCALITIES:
Only found in regions where dikes of this type are exposed, as in New England, particularly in Maine, and at Portland, Connecticut, and San Diego County, California. Well-formed crystals up to an inch or more across are found at Auburn, Maine. Fine-grained aggregates are common in many Maine localities, and are associated with microlite at Dixon, New Mexico. The coarsest crystals form bladed aggregates at Ohio City, Colorado. Foreign localities include: Minas Gerais, Brazil; Madagascar; VarUtrask, Sweden; Southwest Africa; Western Australia; Ural Mountains, Russia and Germany.

USES:
Lepidolite is an ore of lithium and forms in granite masses that contain a substantial amount of lithium. The lithium content in Lepidolite does vary greatly however and low lithium Lepidolite is nearly useless as an ore of lithium. Lepidolite is also used as an ornamental stone and as a heat insulator for industrial purposes. Of course it is also used as a mineral specimen.

FACTS & HISTORY:
cleavage sheets are flexible and elastic, meaning they can be bent and will flex back to original shape. Also some specimens may show triboluminescence.

A rock made of granular pink Lepidolite and red to pink tourmaline is used as an ornamental stone for carving.

Single large plates are often called "books".

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