 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
|
|||||||||||||||||||||
 |
 |
 |
 |
 |
 |
 |
 |
 |
|
|||||||||||||
 |
 |
 |
 |
 |
 |
|
||||||||||||||||
 |
 |
 |
 |
|
||||||||||||||||||
 |
 |
 |
 |
|
||||||||||||||||||
 |
 |
 |
|
|||||||||||||||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||||||||||||||||||||
|
|
|
|
|
|
|
|
|
|
|||||||||||||
|
|
|
|
|
|
|
||||||||||||||||
|
|
|
|
|
||||||||||||||||||
|
|
|
|
|
||||||||||||||||||
|
|
|
|
|||||||||||||||||||
CaZnSi2O6
Monoclinic, C2/c, a = 9.82, b = 9.00, c
= 5.27 Ĺ,
b = 105.6o, Z = 4
 |
|
|
 |
|
|
| Figure 17-6. Dark petedunnite segregations within impure petedunnite (abundant gray) with white and gray calcite from Franklin. Specimen is 10 cm in maximum dimension. Privately owned. Photo by the author. | ||
|
Petedunnite is the rarest of the clinopyroxenes from Franklin. It was described by Essene and Peacor (1987). It is not known from Sterling Hill.
Petedunnite is dark green, with poor {110} cleavage, vitreous luster, and a calculated density of 3.35 g/cm3. Crystals are prismatic to equant, dull in luster, and up to 2 cm in size. Optically, petedunnite is biaxial, positive, 2V = 80o, with a = 1.68, b = 1.69, and g = 1.70; dispersion is strong r > v; and pleochroism is weak with X and Y = light yellow, and Z = light green. There is no discernible fluorescence in ultraviolet; it is a very boring mineral.
Petedunnite is a calcium zinc silicate mineral of the pyroxene group and the Zn analogue of diopside, hedenbergite, and johannsenite.
|
|
|
 |
|
|
| Figure 17-7. Petedunnite crystals (dark gray) in white and gray calcite, associated with indiscernible impure petedunnite, from Franklin. Specimen is 10 cm in maximum dimension. Privately owned. Photo by the author. | ||
|
Solid solution of these components in petedunnite is extensive; Zn is the dominant cation, and the species was defined on the basis of a plurality of Zn. An analysis of petedunnite is presented in Table 10.
Petedunnite occurs on very atypical specimens found on the Buckwheat Dump in Franklin by Richard Bostwick. The specimen (Figure 17-6) consists of dark-green petedunnite crystals, surrounded by light green clinopyroxene and associated with willemite, calcite, genthelvite (the first local occurrence of this species), gahnite, albite, quartz, galena, sphalerite, titanite, apatite, allanite, and other species.
Petedunnite was named in honor of Dr. Pete J. Dunn, a mineralogist.
|
|
|||
|
|
||||
|
||||
| Copyright © 1995 by Pete J. Dunn |
Website
by Herb Yeates
|
|||
|
|
|
|||
|
Link
to homepage
|
||||
|
This
page created: January 11, 2001 |
||||
|
|
|
|||
