Lanthanite-(Ce) occurs as a secondary mineral in oxidized copper ore at the Britannia Mine, Snowdonia, North Wales, U.K. It is found as colorless transparent plates {010} covered by radiating tufts of malachite and is associated with brochantite, posnjakite and chalcoalumite. The analytical formula, based on 17 oxygens, is (Ce0.78La0.55Nd0.55Sm0.09Gd0.05Y0.04)Σ2.06C2.97O9.03 · 7.96H2O, and the theoretical formula is (Ce,La,Nd)2(CO3)3·8H2O with Ce > La,Nd. Orthorhombic, space goup Pbnb, a = 9.482(6), b = 16.938(11), c = 8.965(3)Å, Z = 4, D(calc.) = 2.79 g/cm3 for the ideal formula (Ce:La:Nd = 0.83:0.59:0.58), D (meas.) = 2.76 g/cm3, V = 1440Å3, a:b:c = 0.5598:1:0.5293. Strongest lines in the X-ray powder diffraction pattern are [dÅ (I) (hkl)] 8.47(100)(020), 4.746(65)(200), 4.462(62)(002), 3.255(73)(202) and 3.028(65)(222). The mineral is biaxial negative, α 1.532(2), β 1.594(2), γ 1.616(2); orientation X = b, Y = c, Z = a; 2V(meas.) = 60(2)°, 2V(calc.)=62°, no dispersion observed. The mineral is not fluorescent, and has H = 2.5, a colorless streak, a vitreous luster and is sectile. In dilute mineral acids (HCl, HNO3), the mineral reacts with effervescence to yield a gel-like precipitate of lanthanide(III) hydroxides.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not currently have access to this article.