Formula: Mg2SiO4
Although this is the IMA formula, wadsleyite is actually a sorosilicate (Si2O7 groups) and not a member of the olivine group. The formula Mg4O(Si2O7) better illustrates the structure (Mindat). It is the orthorhombic, high-pressure paramorph of orthorhombic forsterite, orthorhombic poirierite and isometric ringwoodite
Specific gravity: 3.84 calculated
Colour: Light greyish brown
Common impurities: Cr,Mn,Ni,Ca,Zn


Wadsleyite was found initially in the Peace River meteorite from Alberta, Canada; it is thought to be formed from the transformation of olivine during an extraterrestrial shock event, such as a meteorite impact. It is known to be a stable and probably the most abundant phase in the transition zone of the Earth's upper mantle, between 400 and 525km in depth (Mindat).


A the type locality, the Peace River meteorite, Peace River, Alberta, Canada, wadsleyite has been found in the enstatite-ferrosilite - olivine chondritic meteorite. The meteorite is largely an assemblage of olivine, orthopyroxene, plagioclase, iron-nickel alloys and troilite. The plagioglase has been extensively converted to its amorphous equivalent, "maskelynite", which indicates that the meteorite has been subjected to a high-pressure shock event. In addition to this shock-produced phase, the Peace River meteorite contains thin, black, sulphide-rich veins, which pervade the body of the specimen. Typically, within rounded fragments found in these veins, the constituent grains of olivine and orthopyroxene have been transformed into their high-density paramorphs, the spinel-structure ringwoodite and the garnet-structure majorite, respectively. The vein studied in the Peace River meteorite differs significantly from those described in other meteorites, however, in that it contains significant quantities of wadsleyite.
The wadsleyite occurs as microcrystalline aggregates that pseudomorph previously existing olivine fragments within the vein. The wadsleyite-bearing fragments rarely exceed 0.5 mm in diameter, and the actual grain-size of the crystals within the polycrystalline fragments is between 0.5 and 5 microns. The pale fawn, polycrystalline aggregates of wadsleyite are invariablv fractured.
In addition to wadsleyite, the fragments may contain small amounts of majorite or microcrystalline aggregates of pyroxene pseudomorphing majorite and highly faulted ringwoodite (CM 21.29-35).

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