Retzian-(La) is a manganese lanthanum arsenate hydroxide mineral; rare earth elements, chiefly Ce and Nd, proxy for La, as does Y, and Mg substitutes for Mn. Microprobe analysis yielded: MnO 25.2, MgO 3.7, ZnO 1.2, As2O5 26.5, La2O3 10.6, Ce2O3 8.8, Nd2O3 8.2, Pr2O3 5.1, Sm2O3 2.2, Y2O3 2.5, H2O 7.7 (calculated), total = 101.7 wt. %.
Retzian-(La) was described by Dunn et al. (1984c) from Sterling Hill; it has not been found at Franklin.
Retzian-(La) occurs as small (<1 mm) pseudohexagonal crystals, tabular. The luster of crystal faces is variable; most are dull, but is vitreous, as are fracture surfaces. Retzian-(La) is dark reddish brown, transparent, and has a density of 4.2 g/cm3 (meas.), 4.49 g/cm3 (calc.). Cleavage was not observed. It is best identified by both X-ray and chemical methods.
Pleochroism is patchy, varying from pale brown to pale violet-brown; absorption is Z > Y > X; and the orientation is X = c, Y = b, Z = a. There is no discernible fluorescence in ultraviolet.
Retzian-(La) was found but once, in the central zincite zone at Sterling Hill, as euhedral crystals associated with secondary willemite, on a todorokite-covered vein surface in red-willemite/franklinite ore containing much calcite. (Dunn, 1995)

 Location Found: Ogdensburg (Type Locality)
 Formula: (Mn2+,Mg)2(La,Ce,Nd)(AsO4)(OH)4
 Essential Elements: Arsenic, Hydrogen, Lanthanum, Manganese, Oxygen
 All Elements in Formula: Arsenic, Cerium, Hydrogen, Lanthanum, Magnesium, Manganese, Neodymium, Oxygen
 IMA Status: Approved
 To find out more about this mineral at minDat's website, follow this link   Retzian-(La)

Dunn, Pete J. (1995). Franklin and Sterling Hill New Jersey: the world's most magnificent mineral deposits. Franklin, NJ.: The Franklin-Ogdensburg Mineralogical Society. p.678

The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 26, Combined Issue 1985, pg. 10Mineral Notes New To Science, Retzian-(La)
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