 | Hartmann, Léo Afraneo, da Cunha Duarte, Lauren, Massonne, Hans-Joachim, Michelin, Cassiana, Rosenstengel, Leonardo Manara, Bergmann, Magda, Theye, Thomas, Pertille, Juliana, Arena, Karine Rosa, Duarte, Sandro Kucera, Pinto, Viter Magalhães, Barboza, Eduardo Guimarães, Rosa, Maria Luiza C.C., Wildner, Wilson (2012) Sequential opening and filling of cavities forming vesicles, amygdales and giant amethyst geodes in lavas from the southern Paraná volcanic province, Brazil and Uruguay. International Geology Review, 54 (1) 1-14 doi:10.1080/00206814.2010.496253 | Journal (article/letter/editorial) | | lavas from the southern Paraná volcanic province, Brazil and Uruguay a b c Léo Afraneo Hartmann , Lauren...Federal do Rio Grande do Sul, Avenida Bento Gonçalves, Porto Alegre, Rio Grande do Sul, Brazil b Departamento...Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil c Institut für Kristallchemie...Geological Survey of Brazil (CPRM), Rua Banco da Província, Porto Alegre, Rio Grande do Sul, Brazil e Departamento...Geologia, Universidade Federal da Roraima, Rio Branco, Roraima, Brazil Published online: 06 Aug 2010. To cite |  | | Journal (issue) | | Articles 708 Coloured Stone Mining and Trade in Brazil: A Brief History and Current Status By Aurélien...Collection V. L. Villani photo p. 758 Cover Photo: Brazil is the source of a variety of coloured stones,...Gemmology, 35(8), 2017 Gem Notes a b c d cedony (agate), danburite, scapolite, moonstone and kornerupine...Saint-Clair Fonseca Junior (BC Gemas do Brasil, Governador Valadares, Brazil), and heating to 500°C in air was...recently had the pleasure to study two chalcedony/agate cameos that were fascinating for their gemmological |  | | Journal (issue) | | PRECIOUS GEMSTONES, AGATE CAN C) BE USED AS A POLISHER IN INDUSTRY z The colour of agate is highly variable...combinations of all these colours. m VARIETIES OF AGATE I Agate is an impure form of chalcedony. Chalcedony...that forms in micro- • scopically small crystals. Agate is distinguished from chalcedony by its characteristic...gemstone. These bands are not usually visible when the agate specimens are first removed from the ground (many...in form. The best of these patterns can make the agate extremely valuable as a decorative gemstone. There |  | | Journal (volume) | | Editore SpA. • e .,. Crystals of pyrite from Rio Marina on the island of Elba , off the Italian coast...best quality rose quartz comes from Minas Gerais, Brazil; Madagascar; South Africa; and Maine and other...a mineral; chiefly because its crystal particles do not keep the same shape when they are broken down...reveals valuable in themselves, while others they do not fulfil all the necessary criteria , but overall...because of its great distance from the Earth. We do know, however, chat its orbit sometimes cakes it |
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