THE MINERAL CHURCHITE-(Y)

  • Chemistry: (Y, Er)PO4 - 2H2O, Hydrated Yttrium Erbium Phosphate.
  • Class: Phosphates
  • Uses: as a very minor ore of yttrium and erbium and as mineral specimens.
  • Specimens

Churchite-(Y), also known as just churchite and weinschenkite, is a fairly scarce rare earth phosphate. A rare earth mineral is one that contains any of the so called rare earth metals/elements. In this case, it is yttrium and erbium, two industrially valuable metals that are the two rare earth elements in churchite-(Y). The (Y) is for the yttrium which is more significant than the erbium in the chemistry of churchite-(Y). The mineral churchite-(Nd) contains the element Neodymium, another rare earth element.

These are some other rare earth phosphates and their respective chemistries:

    • Florencite (Cerium Aluminum Phosphate Hydroxide)
    • Monazite (various rare earth metals Phosphate)
    • Rhabdophane (Hydrated Cerium Lanthanum Neodymium Yttrium Phosphate)
    • Xenotime (Yttrium Phosphate)

In most of Europe the mineral churchite-(Y) is known as weinschenkite and is named for a famous German mineralogist. Specimens of churchite form interesting cotton-white sprays of fine acicular or hair-like clusters. The sprays are unique and unlike other minerals that form acicular crystals. Although quite hard to describe, the clusters simply must be seen in order to appreciate their unusual character.

PHYSICAL CHARACTERISTICS:

  • Color is white, colorless or gray.
  • Luster is silky to vitreous.
  • Transparency: Specimens are translucent.
  • Crystal System is monoclinic.
  • Crystal Habits include sprays of fine acicular or hair-like clusters also as fibrous crusts and rosettes.
  • Cleavage is perfect but usually not discernible.
  • Fracture is fibrous.
  • Hardness is 3.
  • Specific Gravity is approximately 3.3 (slightly above average for translucent minerals)
  • Streak is white.
  • Other Characteristics: Maybe slightly radioactive.
  • Associated Minerals include limonite, cacoxenite, beraunite and other phosphate minerals.
  • Notable Occurrences are limited to Rockbridge County, Virginia, USA; Auerbach, Germany and Cornwall, England.
  • Best Field Indicators are crystal habit, color, luster, associations and locality.
CHURCHITE specimens:
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CHURCHITE specimen chu-1
$ 30.00
Dims: 1.8 x 1.4 x 1.1" (4.6 x 3.6 x 2.8 cm)
Wt: 1.9 oz. (55 g)
Kelly Bank Mine, Rockbridge County, Virginia, U.S.A.
At least 20 tiny, round Churchite sprays rest on the iron-bearing base of this small hand specimen. Each of these sprays is made up of many microscopic, radiating, acicular Churchite fibers that are far too fine to be studied with a loupe. From what study I can make, they are white in color and have a silky to pearly luster. They may likely be translucent, or even transparent. A few of the sprays have been damaged or crushed, but most are in excellent condition. The base rock is streaked in black and brown and is quite dense; it may be part of a concretion.
no photo
chu-1 ($ 30.00)
Kelly Bank Mine, Rockbridge County, Virginia, U.S.A.
CHURCHITE specimen chu-2
$ 60.00
Dims: 1.01x0.64x0.44" (2.56x1.62x1.11cm)
Wt: 0.16oz (4.4g)
Auerbach, Oberfalz, Germany
Multiple crystals of limonite are cemented together by sprays of churchite-(Y) crystals. Some of the churchite clusters are complete fuzzy balls, but mostly the surface looks more like a fuzzy crust. Many of the surfaces are actually the bases of the churchite crystals, where the host limonite has fallen away. Many of the clusters are broken open, revealing the radial structure of the crystal growth. Note that the churchite is white, and the individual acicular crystals appear translucent. Many of the clusters have a dusting of red-brown limonite.
no photo
chu-2 ($ 60.00)
Auerbach, Oberfalz, Germany
CHURCHITE specimen chu-3
$ 25.00
Dims: 0.43x0.41x0.28" (1.10x1.04x0.72cm)
Wt: 3.3ct (0.66g)
Auerbach, Oberfalz, Germany
This is a crust of churchite-(Y) over a piece of limonite. The churchite is the usual white balls of tiny acicular crystals. Many of the balls are broken open, revealing their radial structure, and also showing that many of the needles have random lengths, lending a rather tossled appearance to the "hair". Much of the otherwise pure white of the churchite has been stained by a dusting of limonite.
no photo
chu-3 ($ 25.00)
Auerbach, Oberfalz, Germany
 

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