Barysilite



Barysilite is a lead manganese silicate. The composition is uniform from specimen to specimen, and solid solution of other cations is limited; Ca and small amounts of Mn may substitute for Pb (Dunn, 1985b). Yeates (1991) noted Ca-enrichment in the latest formed barysilite in a secondary druse. Barysilite was first reported from Franklin by Shannon and Berman (1926) using a very sparse sample from the picking table at Franklin. Additional data were provided by Bauer and Berman (1930). Barysilite was synthesized by Frondel and Ito (1967) and Ito (1968). The literature on synthesis studies is extensive; a review of barysilite-type compounds is given by Schmidt et al. (1983).
Lajzerowicz (1964, 1965) showed that Mn is essential to barysilite and published the description of the structure which consists of non-linear Si2O7 groups, with each Pb atom surrounded by three oxygen atoms.
Barysilite occurs as multi-centimeter-sized lamellar aggregates, platy crystals, gray botryoids, and 1.0 mm white opaque spherules; platy aggregates are the common habit. Druse habits are not uncommon, and epitactic intergrowths with ganomalite were illustrated by Yeates (1991). Barysilite is white, gray, light violet, or commonly light pinkish gray. The luster is vitreous to adamantine to pearly, and the cleavage is perfect. There is no discernible fluorescence in ultraviolet. Its visual appearance, lack of fluorescence, and mineral associations distinguish it from most other local minerals.
Although sparse when first discovered on the picking table, barysilite has since been found in relative abundance in the restricted assemblage of lead silicates. Barysilite occurs in recrystallized assemblages as platy masses associated with hardystonite, clinohedrite, andradite, manganaxinite, willemite, grossular, and nasonite, among other species. Although commonly occurring with nasonite as the only other lead silicate present, minor amounts of margarosanite or hancockite may be associated. Barysilite commonly occurs as a late-stage mineral, forming druses, breccia-cements, and crack-fillers in other species (johannsenite for example), and as fresh material on previously formed fractures and slickensides of other minerals. Among the most prized specimens are those of a barysilite-dominant breccia enclosing fragments of andradite and crystals of bright green willemite. An association with larsenite and ganomalite was observed in one specimen. (Dunn, 1995)


 Location Found: Franklin
     
 
 Year Discovered: 1888
     
 Formula: Pb8Mn2+[Si2O7]3
 Essential Elements: Lead, Manganese, Oxygen, Silicon
 All Elements in Formula: Lead, Manganese, Oxygen, Silicon
     
 IMA Status: Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
     
     
 To find out more about this mineral at minDat's website, follow this link   Barysilite

     
 References:
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.408

Frondel, Clifford (1972). The minerals of Franklin and Sterling Hill, a checklist. NY.: John Willey & Sons. p.44


The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 33, No. 1 - Spring 1992, pg. 18The Lead Silicate Minerals of Franklin, New Jersey: an SEM Survey, Herb Yeates, Barysilite
View IssueV. 28, No. 1 - Spring 1987, pg. 24Mineral Notes Research Reports, The Margarosanite Assemblage, Barysilite
View IssueV. 16, No. 1 - February 1975, pg. 8Mineral Notes - Barysilite (small article)
View IssueV. 10, No. 2 - August 1969, pg. 8Mineral Notes - Barysilite
View IssueV. 9, No. 1 - February 1968, pg. 6Mineralogical Data - Barysilite and Larsenite
View IssueV. 9, No. 1 - February 1968, pg. 10Mineralogical Data - Barysilite
View IssueV. 6, No. 1 - February 1965, pg. 8Barysilite
View IssueV. 4, No. 1 - February 1963, pg. 7Barysilite
     
Images

     
Barysillite coating, andradite garnet, minor franklinite and willemite from Franklin, NJ
Barysillite coating (light pinkish tan), andradite garnet (brown), minor franklinite (black) and willemite (gray) from Franklin, NJ. From the collection of, and photo by JVF.


Barysilite, franklinite, andradite garnet and willemite from Franklin, NJ
Barysilite (pink coating), franklinite (black), andradite garnet (brown) and willemite (light green, pink, white) from Franklin, NJ. 3 7/8" x 2 7/8". From the collection of, and photo by Robert A. Boymistruk.


Platy barysilite, hendricksite mica, minor willemite and franklinite from Franklin, NJ.
Platy barysilite (pink), hendricksite mica (brown), minor willemite (tan) and franklinite (black) from Franklin, NJ. 1 5/8 " x 1 1/4". From the collection of, and photo by Robert A. Boymistruk.







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