METACONGLOMERATE
Metaconglomerates form by metamorphism of conglomerate. The
general shapes of the original gravel are usually well preserved. Metaconglomerates have a clastic texture
and are composed of rounded to subrounded gravel surrounded by finer-grained
matrix. Sometimes, strongly
directed metamorphism results in a stretched-pebble conglomerate, which
has elongated gravel clasts.
Metaconglomerate (“Black Marinace Gold Granite”; sometimes
considered “Black Mosaic Granite”; also apparently (?) known as
“Black Morgan Granite”) - this attractive Precambrian-aged polymict
metaconglomerate from Brazil has small-scale interpenetrating pressure-solution
contacts between clasts in many areas (see lower right, upper central-left,
upper central-right).
Metaconglomerate (“Marinace Green Granite”) - this
Precambrian-aged polymict metaconglomerate from Brazil has clasts are dominated
by igneous & metamorphic rocks. The greenish matrix is epidote-rich.
Metaconglomerate (“Marinace Red Granite”) - another
Precambrian-aged polymict metaconglomerate from Brazil. This rock has a
nice dark reddish-colored matrix and clasts of variable size and composition
(mostly igneous & metamorphic, plus relatively common epidotized
clasts). Other commercial names that appear to have been applied to the
same rock include “Paladium Granite”, “Palladio
Granite”, and “Palladio Vesuvio Granite”.