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Yttrofluorite  (variety of Fluorite)
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Yttrofluorite is named for being a variety of Fluorite with an appreciable amount of yttrium (Y). The name Fluorite is in reference to its fluorine (F) content. Fluorine is named from the Latin word fluere, meaning to flow, because it melts easily and is used as a flux in smelting.

Discovered in 1529 (Fluorite); IMA status: Not Valid (a variety of Fluorite, which is valid)

Chemistry

Chemical Formula:

Ca_0.7Y_0.3F_2.3

[Calcium Yttrium Fluoride]

Molecular Weight:

78.07 gm (Fluorite)

Classification

Mineral Classification:

Halides

Strunz 8th Ed. ID:

3/A.08-10

Nickel-Strunz 10th Ed. ID:

3.AB.25

3 : HALIDES
A : Simple halides, without H₂O
B : M:X = 1:2

Related to:

Fluorite Series and related compounds

Crystal Data

Crystallography:

Isometric - Hexoctahedral

Crystal Habit:

Cubes, octahedra, rarely dodecahedra, or combinations, with many other forms; rounded or stepped, to 2 m; nodular, botryoidal, rarely columnar or fibrous; granular, massive.

Twinning:

Common on [111], interpenetrant, flattened, also as contact twins.

Physical Properties

Cleavage:

[111] Perfect, [111] Perfect, [111] Perfect

Fracture:

Sub-Conchoidal to Uneven

Tenacity:

Brittle

Moh's Hardness:

4.0

Hardness (Vickers):

VHN₁₀₀=174 - 181 kg/mm²

Density:

3.175 - 3.184 (g/cm³) (3.56 if high in rare-earth elements)

Luminescence:

Fluoresces blue, violet, green, yellow, red under UV; may be phosphorescent, thermoluminescent, or triboluminescent.

Radioactivity:

Not Radioactive

Other: 

Slightly soluble in water (0.016 grams per liter at 18°)

Optical Properties

Color:

White to Pale Yellow, Pink

Transparency:

Transparent to Translucent

Luster:

Vitreous, Dull

Refractive Index:

1.432 - 1.448  Isotropic

Birefringence:

0.000 (Isotropic) (Frequently exhibits very weak anomalous birefringence, especially in cleaved, cut or pressed crystals)

Dispersion:

0.007 (very, very low)

Pleochroism:

None

Occurances

Geological Setting (Fluorite):

An accessory mineral in granite, granite pegmatites, syenites; around fumaroles; in carbonatites and alkaline intrusives. Economic deposits in low- to high-temperature hydrothermal veins and stratabound deposits; a cement in sandstones.

Common Associations (Fluorite):

Apatite, Barite, Calcite, Cassiterite, Celestine, Dolomite, Quartz, Scheelite, Sulfides, Topaz, Wolframite

Common Impurities (Fluorite):

Y, Ce, Si, Al, Fe, Mg, Eu, Sm, O, ORG, Cl, TR

Type Locality:

Hundholmen, Tysfjord, Nordland, Norway

Year Discovered (Fluorite):

1529

View mineral photos:

Yttrofluorite Mineral Photos and Locations

More Information

Mindat.org  (Yttrofluorite)
Mindat.org  (Fluorite)
Webmineral.com  (Fluorite)

Yttrofluorite is an extremely rare variety of Fluorite that contains an appreciable amount of yttrium (Y).

Originally reported from Hundholmen, Tysfjord, Nordland, Norway. Several other localities have been reported including Janet ore occurrence, Kara-Oba W deposit, Betpakdala Desert (Bet-Pak-Dal Desert), Qaraghandy Oblysy (Karaganda Oblast'), Kazakhstan; Drag, Ploskaya Mt, Western Keivy Massif, Kola Peninsula, Murmanskaja Oblast', Northern Region, Russia.

In the USA there are two localities both located in Colorado: the Little Patsy pegmatite (Patsy pegmatite), South Platte Pegmatite District, Jefferson County; Strang Pegmatite Occurrence (S. B. Strang Ralston Creek Pegmatite), Clear Creek Pegmatite Province, Jefferson County.
 

  
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