Origin of optical variations in grossular andradite
com, Fallbrook, California, USA, for rough pieces of iridescent andradite
from Mexico and a slab of jadeite from Russia.
Almandine, spessartine, grossular, uvarovite, andradite
and pyrope are six minerals which are regarded as belonging to the garnet family.
The most spectacular piece is a combination specimen of sphalerite, quartz, andradite
and hedenbergite over 25 cm in diameter.
The following standards and were used: Al on sanidine, Ca on titanite, Cl on NaCl, Cr on chromite, F on topaz, Fe on andradite
, K on orthoclase, Mg on olivine, Mn on spessartine, Na on albite, Nb on columbite, Si on titanite, Ti on titanite and Zn on gahnite.
Demantoid garnet is a rare and beautiful bright grass green sub-variety of andradite
Epidote, chrolite, andradite
and apatite have also been identified.
Andrada was the first to describe petalite, seapolite and cryolite; the mineral species andradite
was named for him.
In 2009 some of the world's finest specimens of green and yellow andradite
crystals on matrix were found in a mangrove swamp near Antetezambato in the extreme northern area of Madagascar.
One could not think of leaving Africa without a check-in on specimens from the new occurrence of gemmy green andradite
variety "demantoid" at Antetezambato, Antsiranana, Madagascar.
Leaving the African treasure-chest and heading for Asia by way of Madagascar, we pause to note the very exciting new andradite
specimens (marketed as the variety "demantoid") now being gathered from open-pit workings in skarn rock near the village of Antezambato, near the town of Ambanja, in Antsiranana Province.
The 2009 Denver Show (see report in this issue) was graced by abundant supplies of the lovely new andradite
("demantoid") specimens now coming from diggings in a mangrove swamp at Antezambato, Antsiranana Province, on the northern coast of Madagascar.