Description
Fergusonite-Y is one of the few minerals which contains Dysprosium, as well as many other of the Rare Earth Elements, and you can bring it home to add to your collection!
Wikipedia says that some Yttrium-dominant minerals such as Fergusonite may contain as much as 7% dysprosium, and that no dysprosium-dominant mineral is known to exist and dysprosium is “never encountered as a free element”.
Mindat has a specimen that was sampled and shown to contain: 45.2% Nb₂O₅, 28.46% Y₂O₃, 5.09% UO₂, 4.44% Ta₂O₅, 3.79% Yb₂O₃, 3.09% Dy₂O₃, 1.76% Gd₂O₃, 1.58 % CaO, 1.39 & Sm₂O₃, 1.04% Er₂O₃, 1.01% Lu₂O₃, 0.51% Nd₂O₃, and 0.31% ThO₂, with 7% accounting for other unrelated molecules.
Fergusonite-(Y) occurs here as a pale tan to cream colored vein sandwiched between cleavages of mica and associated with plagioclase feldspar. Its hardness is between 5½ – 6½, and specific gravity of around 5.7.
Fergusonite-Y is known to occur in at least a couple hundred localities on most continents and in six Colorado counties, mostly near pegmatites.
Keep an eye out for this valuable rock on your next hike!
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