Datolite is a
rare collector's gem not often seen in the gem market.
Faceted gems are very brilliant even though their
dispersion (fire) is low. It is often found in basalt
vesicles along with Calcite and
and is often confused with certain Zeolites because
of its luster, color and associations.
Although sources are worldwide,
many Datolite gems come from US material. US sources
are Hampden County, Massachusettes; Hartford County,
Connecticut; Essex County and Passaic County, New Jersey;
Loudoun County, Virginia. Worldwide sources are Arendal,
Norway (the Type Locality); Harz Mountains, Germany; Italy; Habachtal, Austria;
Iwato Copper Mine, Japan; Charcas,
San Luis Potosi, Mexico and exceptional, pale yellow
crystals from Dal'negorsk, Primorskiy Kray, Russia.
Datolite is also found in the Lake Superior region of Michigan. It is associated
with native copper at
this location and is found in porcelain-like masses and nodules. The nodules are
brown to off white in color and some are cut and polished as an ornamental stone.