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Yttrocrasite-(Y)
Current inventory:  0 gems
 

Chemistry:  (Y,Th,Ca,U)(Ti,Fe)₂(O,OH)₆  
[Yttrium Thorium Calcium Uranium Titanium Iron Oxide Hydroxide]

Discovered in 1906;   IMA status: Valid (pre-IMA; Grandfathered).
Yttrocrasite-(Y) is named from a dominance of yttrium in the composition and the Greek word "krasis" meaning many, alluding to the many other elements present in addition to yttrium.

Classification

Mineral Classification:

Oxides

Strunz 8th Ed. ID:

4/D.19-20

Nickel-Strunz 10th Ed. ID:

4.DG.05

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
G : With large (+- medium-sized) cations; chains of edge-sharing octahedra

Related to:

Euxenite Group. Polycrase-(Y) - Loranskite-(Y) Series. A poorly characterised, metamict mineral. Compare Polycrase-(Y).

Crystal Data

Crystallography:

Orthorhombic or Amorphous. Metamict (may have been orthorhombic before metamictisation).

Crystal Habit:

Crystals rough, showing three pinacoids, a prism, and an orthodome.

Twinning:

None

Physical Properties

Cleavage:

None

Fracture:

Irregular/Uneven, Sub-Conchoidal

Tenacity:

Brittle

Hardness (Mohs):

5.5 - 6.0

Density:

4.80 (g/cm³)

Luminescence:

None

Radioactivity:

Strong; GRapi = 784,722.58 (Gamma Ray American Petroleum Institute Units)

Optical Properties

Color:

Black, Brown where altered; in transmitted light, Amber-Yellow to light Yellow

Transparency:

Opaque. Translucent on thin edges

Luster:

Resinous

Refractive Index:

n = 2.12 - 2.15  Isotropic

Birefringence:

0.00 (Isotropic)

Dispersion:

Strong

Pleochroism:

None

Anisotrophism:

Weakly anisotropic in part

Occurances

Geological Setting:

Precambrian granites, pegmatites, and metamorphic rocks.

Type Locality:

Clear Creek pegmatite, Burnet County, Texas, USA

Year Discovered:

1906

View mineral photos:

Yttrocrasite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Yttrocrasite-(Y) is a very rare radioactive mineral. Faceted gems are extremely rare and really only faceted as a collector's oddity. Yttrocrasite-(Y) is strongly radioactive due to the presence of Thorium (7.79%) and Uranium (7.99%).

There are only a few locations for finding Yttrocrasite-(Y): Chudnoe Pd-Au deposit, Grubependity lake, Komi Republic, Northern Region, Russia; Åskagen (Torskebäcken), Filipstad, Värmland, Sweden; and the Type Locality of Clear Creek pegmatite, Burnet County, Texas, USA.
 

  
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