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Formula: Ca16(Mg,Li)2[B13O17(OH)12]4Cl6.28H2O
Hydrated megaborate, lithium-bearing
mineral
Crystal System: Orthorhombic
Specific gravity: 2.07 measured, 2.05 calculated
Hardness: 3
Streak: White
Colour: Colourless
Luminescence: No fluorescence with either short wave or long wave UV
Environments
Although walkerite was approved in 2001, to date (December 2024) it has been reported only from the
type locality.
Localities
At the type locality, the Potash Corporation of Saskatchewan Mine, Penobsquis, Cardwell Parish, Kings county, New
Brunswick, Canada, walkerite occurs in the lower third of the Upper Halite Member, within a thick sequence of
marine evaporites.
The presence of borate minerals from two potash mines in the Penobsquis–Sussex
area was first noted in the early 1980s in residue from the drilling operations. The
list of borate minerals includes boracite, veatchite, colemanite,
danburite, hilgardite-1A,
hilgardite-4M, howlite,
hydroboracite, priceite,
szaibélyite, ulexite,
volkovskite, pringleite,
ruitenbergite, trembathite,
strontioginorite, congolite,
tyretskite, ginorite,
inyoite and penobsquisite. Other minerals found
with the borate assemblage include
anhydrite,
sellaite, fluorite,
nickeline, pyrite,
chalcopyrite, sphalerite,
halite, sylvite,
microcline, diopside,
quartz, a mica group mineral, a
clay mineral, hematite,
limonite, magnesite,
calcite, dolomite,
monohydrocalcite and
malachite. Organic material is present in several sections of core.
Walkerite was found in drill core intimately associated with halite,
hydroboracite, hilgardite,
volkovskite, boracite,
szaibélyite, the mica group
mineral and anhydrite. Approximately 100 single crystals with a total
approximate weight of 30 mg were separated, along with numerous bundles of fibres.
Walkerite exhibits a fibrous to bladed morphology and the fibres commonly occur in bundles up to 7 mm in length and
individual acicular crystals to 2 x 0.05 mm. The crystals are transparent to translucent, colourless to white, with a
white streak and vitreous lustre
(CM 40.6.1675-1686).
Walkerite from Penobsquis - Image
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