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 Arige 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.