Geology

Calcareous concretion

Calcareous concretions occur in round shapes and are found in layers of clay. They are segmented in compartments by contraction fissures filled with calcite, constituting a septarium. The pink coloration is given due to the presence of iron oxide. This sample was collected in 1870 by Antonio Carlos Melo, scientist of the National Museum, and comes from the region between the municipalities of São Gabriel and Alegrete, Rio Grande do Sul.

Sedimentary gap in Antarctica

Sedimentary rock of the Cretaceous period — Whisky Bay Formation, Grupo Gustav, Larson Basin — collected at the Bibby Point beach, in the North of the James Ross Island, during the first expedition of a team of geologists a paleontologists from the National Museum in Antarctica, in January and February of 2007.

Quartz Sample

Rhombohedral quartz crystal, with 3 cm of width by 8 cm of height, under crystal mass of green tourmaline, with 24 cm of width by 4 cm of height.

Sample donated by President Getúlio Vargas to the National Museum in 1940.

Carbonate concretion in Antarctica

Carbonate concretion in fine sandstone with crossed laminations, of the Cretaceous period — Lachman Craigs Member, Santa Marta Formation, Larsen Basin —, collected in Col. Crame, North of the James Ross Island, during the first expedition of a team of geologists and paleontologists of the National Museum in Antarctica, in January and February of 2007.

Galena Sample

Various cubic Galena crystals, of various sizes, grown on fine calcareous rock with 12 cm of length by 8 cm of width.

Collected in California, in the United States of America.

Calcite sample

“Dog tooth” calcite crystals, with 4 cm of width and length, encrusted on a Galena crystal with 5 cm of length and width.

Collected in California, in the United States of America.

Sample of Pisolitic Limestone

The São José de Itaboraí Basin, located in the municipality of Itaboraí, Rio de Janeiro, is one of the smallest Brazilian sedimentary basins and one of the most important fossil sites of Paleocene age in Brazil and in the world. It was discovered in 1928 and had its limestone explored by the cement industry until depletion. The pisolitic limestone, the most notable lithology of the basin, can no longer be found.

Angra dos Reis Meteorite

Its fall, in January of 1869, in front of the Bonfim church, at Praia Grande, in Angra dos Reis, Rio de Janeiro, was witnessed by Joaquim Carlos Travassos and two of his slaves. These last ones recuperated two fragments out of approximately 2 meters of depth, one of which was donated to the National Museum. The Angra dos Reis meteorite gave name to a new group of meteorites, the Angrites, considered the oldest rock in the solar system.

Pará de Minas Meteorite

The sample shows the Widmanstätten pattern, typical of metallic meteorites when they are attacked by acid. This structure is formed as consequence of a very slow cooling — approximately1º C per each 1 million years — in the nucleus of a planetary body probably similar to the Earth’s.