Xenotime has two directions of perfect prismatic dichroic with pink, yellow or yellowish brown seen in the extraordinary ray and brownish yellow, grayish brown or greenish brown seen in the ordinary ray.
22.
Such crystals closely resemble xenotime in appearance and, indeed, were for a long time supposed to belong to this species, the special name " wiserine " being applied to them.
23.
Thus, among the anhydrous rare earth phosphates, it is the tetragonal mineral xenotime that incorporates yttrium and the yttrium earths, whereas the monoclinic monazite phase incorporates cerium and the cerium earths preferentially.
24.
The principal commercial sources of erbium are from the minerals xenotime and euxenite, and most recently, the ion adsorption clays of southern China; in consequence, China has now become the principal global supplier of this element.
25.
Since xenotime contains a uranium isotope that decays at a known rate into lead, analyzing the amount of lead and uranium in a sample gives a measure of how long ago the xenotime was formed, and thus the sedimentation began.
26.
Since xenotime contains a uranium isotope that decays at a known rate into lead, analyzing the amount of lead and uranium in a sample gives a measure of how long ago the xenotime was formed, and thus the sedimentation began.
27.
Of the above yttrium minerals, most played a part in providing research quantities of lanthanides during the discovery days . Xenotime is occasionally recovered as a byproduct of heavy sand processing, but is not as abundant as the similarly recovered monazite ( which typically contains a few percent of yttrium ).
28.
For example, ytterbium ( reserves about 1 M tons ) and yttrium, 400 times more common, with middle capturing values, can be found and used together without separation inside minerals like xenotime ( Yb ) ( Yb 0.40 Y 0.27 Lu 0.12 Er 0.12 Dy 0.05 Tm 0.04 Ho 0.01 ) PO 4, or keiviite ( Yb ) ( Yb 1.43 Lu 0.23 Er 0.17 Tm 0.08 Y 0.05 Dy 0.03 Ho 0.02 ) 2 Si 2 O 7, lowering the cost.
