"Marinace Green Granite" - metaconglomerate from the Precambrian of Brazil.
This attractive decorative stone is a greenish, Precambrian-aged, polymict metaconglomerate from Bahia State in eastern Brazil. Available clast lithology compilations indicate that this rock is dominated by pebbles and granules of granite, gneiss, and mafic igneous rocks. Some clasts have been partially epidotized. The matrix is a pleasant greenish color, dominated by epidote, quartz, and tremolite.
The pebbles and cobbles making up this metaconglomerate were originally deposited during the Mesoproterozoic, in a rift basin alluvial fan environment. The resulting sedimentary rock was subjected to hornfels-grade metamorphism (high-temperature, low-pressure) at ~1.5 Ga during the intrusion of nearby mafic igneous rocks. Subsequent regional metamorphism occurred during the Brazilian-Pan African Orogenies in the late Neoproterozoic (550-650 Ma).
Stratigraphy: Ouricuri do Ouro Formation, lower Pajeú Synthem, Oliveira dos Brejinhos Group, Espinhaço Supergroup, Mesoproterozoic, ~1.6 to 1.7 Ga
Locality: apparently derived from a commercial quarry near Morpará or near Caetité, Bahia State, eastern Brazil
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Some info. derived from:
Danderfer et al. (2009) - New geochronological constraints on the geological evolution of Espinhaço Basin within the São Francisco Craton - Brazil. Precambrian Research 170: 116-128.
Siddall (2016) - There's an awful lot of conglomerates in Brazil: 'Monolith & Shadow' revisited. Geology Today 32: 205-207.
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