Synonyms: |
Chiquitanita,
Chrome-Chrysoprase, Chrome-Chalcedony, Chromium Chalcedony,
Mtorodite, Mtorolite
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Chiquitanita
is a trade name (marketing term) for a rare green, chromium-bearing
variety of Chalcedony from the Chiquitania region (Chiquitos
Province) of Bolivia. It is the same material often
called "Mtorodite" or "Mtorolite"
after the discovery near the mining town of Mtoroshanga,
Mashonaland West, Zimbabwe. By any of these names, Chiquitanita,
Mtorodite, Mtorolite or Chrome-Chalcedony, they are all a
variety of Chalcedony
colored by small quantities of chromium. They are all
similar in appearance to the better known Chrysoprase,
but differ in that Chrome Chalcedony is colored by chromium
while Chrysoprase is colored by
nickel. The two can be distinguished with a Chelsea
color filter, as Mtorodite (chrome Chalcedony) will
appear red, and Chrysoprase will appear green. Chrome
Chalcedony,
unlike Chrysoprase, may also contain tiny black specks
of chromite. Chrome Chalcedony, along with Agate, Carnelian,
Chrysoprase, Heliotrope (blood stone), Onyx and others,
are all varieties of Chalcedony which is a cryptocrystalline
form of Quartz.
Chrome Chalcedony was widely used in jewellery and seals throughout the Roman Empire. Its earliest use appears to have occurred around
the first century AD and then disappeared from use sometime in the second century.
The source of this material is unclear. Pliny the Elder described it as coming from India, but
no deposits have been found there. It may have come from Anatolia (in modern day Turkey) where deposits are known to exist.
Chrome Chalcedony was not "discovered" again
until 1955 near the mining town of Mtorochanga in Zimbabwe. A small number of other sources of
chromium-bearing Chalcedony have been reported since the mid-1980's. It has also been discovered in western Australia; Saricakaya,
Eskisehir, Central Anatolia, Turkey; Ural mountains,
Russia and from Rincón del Tigre, Chiquitos Province, Santa Cruz Department, Bolivia.
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