Wawayandaite



Wawayandaite is a calcium manganese boron beryllium silicate hydroxide-chloride mineral and is not known to be related to other species. The chemical composition is SiO2 28.2, MgO 1.9, CaO 24.8, ZnO 1.1, MnO 9.8, B2O3 3.8, BeO 17.6, H2O 9.6, Cl 3.0, less 0 = Cl 0.7, total = 99.1 wt. %.
Wawayandaite was first described by Dunn et al. (1990) from Franklin. It is not known from Sterling Hill or elsewhere. The crystal structure has not been investigated.
Wawayandaite occurs as colorless platy crystals; some are euhedral, sharp, tabular and twinned, but these are rare. Most crystals are severely curved and are very thin and transparent. Locally, wawayandaite resembles some diaphanous, late-stage barysilite, talc, or prehnite. Wawayandaite is also known in exceedingly fine-grained, clay-like aggregates. Wawayandaite is colorless, but may appear white or silvery in the aggregate.
The luster is very pearly on curved crystals and slightly pearly on euhedral crystals and clay-like aggregates; cleavage is apparently perfect. Wawayandaite is extremely soft. Density determinations are unreliable; the calculated density is 2.98 g/cm3.
There is no discernible pleochroism or fluorescence in ultraviolet.
Wawayandaite occurs in a classic Franklin vein assemblage consisting of druse andradite on calcite-poor franklinite-willemite ore. Superb 6 x 1 mm, prismatic willemite crystals and 5 mm, equant, rhombic calcite crystals occur on this druse. These are partially coated with a druse of dull reddish-brown friedelite. Hodgkinsonite crystals and twinned cahnite crystals are rarely associated. Wawayandaite occurs last in this assemblage, in all of the above-cited habits. These specimens were found prior to 1923; they were in collectors' hands by then. This mineral was likely preserved by serendipity, as a minor mineral associated with superb, attractive willemite crystals.
Wawayandaite was noted by [Dunn] in another assemblage, preserved only as a micromount mineral specimen. In this assemblage, franklinite ore is irregularly coated by a calcite druse followed by pyrochroite crystals and, separately, by a pink sussexite druse intergrown with brown prismatic gageite which persists through the sussexite crystallization sequence. Wawayandaite is the latest mineral to form, occurring intergrown with gageite, and persisting after gageite has formed. In this assemblage it occurs as slightly fibrous, curved, white aggregates.
Wawayandaite was found in yet a third assemblage in which it occupies vugs in altered willemite-franklinite-andradite ore. The vuggy areas are coated with druses of hodgkinsonite and fluorite; wawayandaite occurs as platy pearly crystals occurring on these previously formed minerals. (Dunn, 1995)


 Location Found: Franklin (Type Locality), unique to Franklin/Ogdensburg area
     
 
 Year Discovered: 1988
     
 Formula: Ca6Mn2BBe9Si6O23(OH,Cl)15
 Essential Elements: Beryllium, Boron, Calcium, Hydrogen, Manganese, Oxygen, Silicon
 All Elements in Formula: Beryllium, Boron, Calcium, Chlorine, Hydrogen, Manganese, Oxygen, Silicon
     
 IMA Status: Approved 1988
     
     
 To find out more about this mineral at minDat's website, follow this link   Wawayandaite

     
 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.517


The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 31, No. 2 - Fall 1990, pg. 16New to Science Wawayandaite
     
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