 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
|
|||||||||||||||||||||
 |
 |
 |
 |
 |
 |
 |
 |
 |
|
|||||||||||||
 |
 |
 |
 |
 |
 |
|
||||||||||||||||
 |
 |
 |
 |
|
||||||||||||||||||
 |
 |
 |
 |
|
||||||||||||||||||
 |
 |
 |
|
|||||||||||||||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||||||||||||||||||||
|
|
|
|
|
|
|
|
|
|
|||||||||||||
|
|
|
|
|
|
|
||||||||||||||||
|
|
|
|
|
||||||||||||||||||
|
|
|
|
|
||||||||||||||||||
|
|
|
|
|||||||||||||||||||
(Ca,Na)3(Mn,Mg)2(AsO4)3
Cubic, Ia3d, a = 12.500 Å
 |
|
|
 |
|
|
| Figure 25-30. Vein of manganberzeliite with white calcite border cuts Franklin ore composed of franklinite and willemite. Specimen is 7 cm in maximum dimension. Smithsonian Institution, #163870. Photo by the author. | ||
|
Manganberzeliite was first described from Franklin by Frondel and Ito (1963); it has not been found at Sterling Hill.
Manganberzeliite occurs as massive granular material in veins. It is orange-yellow, with vitreous luster, and a density of 4.21 g/cm3. It is isotropic with n = 1.770; there is no discernible fluorescence in ultraviolet. It is best verified using both optical and X-ray methods.
Manganberzeliite is a sodium calcium manganese arsenate mineral, related to the garnet group. An analysis by Jun Ito is given in Table 25; the small amount of Si is likely part of the composition of the mineral and not due to contamination. Numerous unpublished analyses by the writer show that Franklin manganberzeliite has the following compositional ranges: SiO2 0.4-0.6, Al2O3 0.0-0.5, FeO 0.4-0.6, MgO 1.5-2.6, CaO 18.9-19.4, Na2O 4.9-5.3, MnO 19.2-20.9, ZnO 0.0-1.0, and As2O5 53.1-55.9 wt. %.
Manganberzeliite occurs as veins up to 15 mm wide in franklinite/willemite ore (Figure 25-30). The veins are simple ones, either with manganberzeliite alone, or with a thin rim of calcite adjacent to the ore. John L. Baum (pers. comm.) considered this occurrence to be of limited extent, an observation supported by the closely agreeing analytical data for different specimens.
Another Franklin assemblage, represented by fewer specimens, consists of highly calcic ore cut by a vein. The vein filling has calcite and willemite at its margins, followed by a mixture of pink sarkinite and white hedyphane; the center of the vein is composed of manganberzeliite. Schallerite is present as very small crystals in calcite.
|
|
|||
|
|
||||
|
||||
| Copyright © 1995 by Pete J. Dunn |
Website
by Herb Yeates
|
|||
|
|
|
|||
|
Link
to homepage
|
||||
|
This
page created: January 11, 2001 |
||||
|
|
|
|||
