 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
|
|||||||||||||||||||||
 |
 |
 |
 |
 |
 |
 |
 |
 |
|
|||||||||||||
 |
 |
 |
 |
 |
 |
|
||||||||||||||||
 |
 |
 |
 |
|
||||||||||||||||||
 |
 |
 |
 |
|
||||||||||||||||||
 |
 |
 |
|
|||||||||||||||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||||||||||||||||||||
|
|
|
|
|
|
|
|
|
|
|||||||||||||
|
|
|
|
|
|
|
||||||||||||||||
|
|
|
|
|
||||||||||||||||||
|
|
|
|
|
||||||||||||||||||
|
|
|
|
|||||||||||||||||||
KAl2(Si3Al)O10(OH)2
Monoclinic
Muscovite, a potassium aluminum silicate hydroxide mineral of the mica group, is a minor mineral locally, but occurs widely distributed. It was reported from the Franklin Marble in greenish platy masses by Palache (1935) and also by Yau et al. (1984). It was reported from the calcium-silicate units of the Franklin orebody, the local gneisses, and pegmatites by Frondel (1972), and from the Buckwheat Dolomite by Peters et al. (1983). It was reported from Sterling Hill by Frondel (1972). It comprises part of the pseudomorphous “crystals” known locally as algerite (Hunt, 1849), an altered scapolite. Energy-dispersive analysis shows only K, Al, and Si. Muscovite may be more common than recognized to date, particularly in feldspar- and scapolite-bearing assemblages, as colorless, platy crystals with perfect cleavage.
The only muscovite from the Franklin orebody which is noteworthy or distinctive is a barian muscovite, originally described by Bauer and Berman (1933) and to which they applied the name barium-muscovite; some specimens improperly have been called oellacherite by collectors. This material was re-examined by Heinrich and Levinson (1955) who noted that it formed as an alteration of a feldspar, provided X-ray powder data, and stated that this was the 1M polytype.
This barian muscovite is unlike common micas in its physical appearance: it is fine-grained; cleavage is not evident; the color is a deep violet-pink; and it has a dull grainy luster. It occurs in 5-10 cm masses and is associated with an unanalyzed mica, andradite, and copper. Bauer and Berman (1933) reported an association with microcline. This material was re-examined by Dunn (1984), who noted the presence of both hyalophane and abundant barite inclusions, and found a much lower barium content than published by Bauer and Berman (1933); the new values for BaO and K2O (Table 13) are nearly the reverse of those given earlier. Nothing is known of its geologic occurrence.
 |
|
|||
|
|
||||
|
||||
| Copyright © 1995 by Pete J. Dunn |
Website
by Herb Yeates
|
|||
|
|
|
|||
|
Link
to homepage
|
||||
|
This
page created: January 14, 2001 |
||||
|
|
|
|||
