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Formula: CaTa2O6
Multiple oxide, aeschynite group,
tantalum-bearing mineral
Crystal System: Orthorhombic
Specific gravity: 6.402 measured, 6.394 calculated
Hardness: 4½
Streak: White
Colour: Pale creamy white to pale reddish pink, pale yellowish brown to dark brown; In transmitted light the fresh
mineral is transparent and pale creamy-white to reddish-pink
Luminescence: Generally nonfluorescent under UV Some rynersonite, however, is weakly fluorescent pale
yellow-green under short wave UV light and cathode luminescent pale blue; this may be due to the presence of
intimately admixed fersmite, which consistently shows pale yellow-green
fluorescence, strong under short wave UV and weak under longwave, and light blue cathode luminescence on specimens
from this locality (AM 63: 709-714)
Solubility: soluble in both hot and cold mineral acids
Environments
Rynersonite is an alteration product of earlier
niobium-tantalum minerals in some
granite
pegmatites (Webmin).
Localities
At Wampewo Hill, Busiro county, Wakiso, Central Region, Uganda, rynersonite occurs with
microlite in pseudomorphs
after bismutotantalite (Dana). Associated minerals include
microlite, wodginite,
zircon, lepidolite and
quartz
(HOM).
At the Himalaya Mine, Gem Hill, Mesa Grande Mining District, San Diego County, California, USA, rynersonite
occurs as an alteration product of
stibiocolumbite-stibiotantalite
crystals, associated with fersmite and
antimony-bearing microlite
(Dana).
At the type locality, the San Diego Mine, Gem Hill, Mesa Grande Mining District, San Diego county, California, USA,
rynersonite occurs in felted aggregates, often intimately associated with
fersmite as a primary
alteration product of
stibiocolumbite-stibiotantalite
within the gem-bearing portion of the Himalaya
pegmatite-aplite
dike complex. Aggregates of rynersonite are as much as several centimeters in size. Other minerals
found with rynersonite are pink tourmaline,
quartz, albite variety cleavelandite,
cassiterite, tin- and
antimony- bearing microlite, and
beyerite.
One of the two specimens studied is an unusually large sample several centimetres in length. The core is transparent
yellow stibiotantalite; alteration products on the outer margins
consist chiefly of pinkish-creamy-white fibrous rynersonite and a thin discontinuous rind of golden-yellow
fersmite and antimony-bearing
microlite. The other specimen is a
primary
stibiotantalite crystal, showing strong compositional zoning. A thin
rind of rynersonite occurs immediately adjacent to the
stibiotantalite. The rynersonite is itself sharply zoned
outward to fersmite. In both specimens rynersonite and
fersmite are alteration products of
stibiotantalite, and are always accompanied by minor amounts of
antimony-bearing microlite. The
fersmite on both specimens formed later than the rynersonite
(AM 63: 709-714).
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