TECTONIC BRECCIAS
Tectonic breccias in the commercial decorative stone
trade are typically called “marbles”. By definition, any
breccia will have abundant large angular fragments. The tectonic breccias
are generated by intense tectonic crushing and fracturing along fault zones in
orogenic belts. Cut & polished samples are typically bicolored or
multicolored and are quite striking in appearance.
French Grand Antique Marble (field of view 10.9 cm across) - an attractive black
& white tectonic limestone breccia from southern France. It has large
to small angular fragments of black micritic limestone surrounded by whitish
carbonate cement. It has been quarried for millennia (known Roman names
for this rock include “Marmor Celticum” and “Marmor Aquitanicum”).
The rock was exploited in Roman & Byzantine times, then abandoned and
forgotten. Quarrying resumed after rediscovery in the 1700s, but the area
is now exhausted (it’s an “extinct” rock). This
material came from an old quarry at Aubert, just southeast of Moulis, Lez River
Valley, southwest of Saint-Girons, western Ariège Department, central
Pyrenees Mountains, far-southern France.
Italian Red Antique Marble - a tectonic marble breccia from Italy having white
calcite veining and some greenish serpentinization. This material comes
from Genoa in Liguria Province, northwestern Italy.