Allanite

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Allanite
Radioactive if uranium and/or thorium-rich
References[2][3][4]

Allanite (also called orthite) is a

rare-earth elements, and the M sites admit Al3+, Fe3+, Mn3+, Fe2+, or Mg2+ among others.[5] However, a large amount of additional elements, including Th, U, Be, Zr, P, Ba, Cr and others may be present in the mineral. The International Mineralogical Association lists four minerals in the allanite group, each recognized as a unique mineral: allanite-(Ce), allanite-(La), allanite-(Nd), and allanite-(Y), depending on the dominant rare earth present: cerium, lanthanum, neodymium or yttrium
.

Allanite crystals on smoky quartz from the White Mountain Wilderness, Lincoln County, New Mexico, USA (size: 2.7 × 1.8 × 1.7 cm)

Allanite contains up to 20% rare-earth elements and is a valuable source of them. The inclusion of

metamict. The age of allanite grains that have not been destroyed by radiation can be determined using different techniques.[6]

Allanite is usually black in color, but can be brown or brown-violet. It is often coated with a yellow-brown alteration product,

specific gravity of 3.5–4.2. It is also pyrognomic
, meaning that it becomes incandescent at a relatively low temperature of about 95 °C.

It was discovered in 1810 and named for the Scottish mineralogist Thomas Allan (1777–1833).[2] The type locality is Aluk Island, Greenland,[3] where it was first discovered by Karl Ludwig Giesecke.

See also

References

  1. S2CID 235729616
    .
  2. ^ a b Allanite-(Ce). Handbook of Mineralogy
  3. ^ a b Allanite. Mindat.org./
  4. ^ Allanite. Webmineral.
  5. ^ Dollase, W. A. (1971). "Refinement of the crystal structure of epidote, allanite, and hancockite" (PDF). American Mineralogist. 56: 447–464.
  6. S2CID 51734682
    .
  7. ^ Klein, C., Dutrow, B. (2007) Manual of Mineral Science. Wiley Publishers, p. 500.
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