Precious Brazil: the Wealth of Gem-Minerals

By MM Gerdau - Museu das Minas e do Metal

MM Gerdau - Museum of Mines and Metal

The MM Gerdau - Museum of Mines and Metal opens its collection and presents a selection with some of the most iconic Brazilian gem minerals. Explore the curiosities, occurrences, colors and shapes in detail.

Bicolor Tourmaline (Rough and Faceted) (2021-03-30) by Lucas D'AmbrosioMM Gerdau - Museu das Minas e do Metal

The exposition “Precious Brazil: the wealth of gem-minerals” presents a small sample of the great gemological variety found in brazilian territory. Within this thematic clipping, the MM Gerdau will show a part of its collection aiming to present Brazil as one of the biggest gem mineral exportation countries in the world and as an important place of first occurrence of some kinds of gem minerals such as: Brazilianite, Euclase and Paraiba Tourmaline .The Brazil’s precious stones production is mostly done by garimpeiros (kind of independent prospectors) and occurs widely spread in many states, for instance, Bahia, Espírito Santo, Goiás, Pará, Piauí, Rio Grande do Sul, Tocantins and mainly in Minas Gerais, from where the majority of variety of gem minerals comes from.

Bicolor Tourmaline. They can incorporate a range of chromophore chemical elements such as Iron, Manganese, Titanium and Cupper, being capable of presenting color zoning in a single crystal. Chemical composition: Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH) - Silicates.

Rough Amethyst (2021-03-30) by Leonardo MirandaMM Gerdau - Museu das Minas e do Metal

Purple variety of quartz. In Ametista do Sul- Rio Grande do Sul (world capital of amethyst stone) it is situated the world biggest deposit of this mineral. Chemical composition: SiO2 - Silicates.

Faceted Amethyst (2021-03-30) by Lucas D'AmbrosioMM Gerdau - Museu das Minas e do Metal

Deep purple Amethyst with step cut. The step cutting styles are indicated to emphasize stone colors. Chemical composition: SiO2 - Silicates.

Amethyst (2021-03-30) by Lucas D'AmbrosioMM Gerdau - Museu das Minas e do Metal

Rough Emerald (2021-03-30) by Marcílio GazzinelliMM Gerdau - Museu das Minas e do Metal

Emerald is one of the most expensive gems. One of the biggest emerald samples in the world was found in the state of Bahia. Itabira and Nova Era, in the state of Minas Gerais, are currently famous for the extraction of quality stones. Chemical composition: Be3Al2Si6O18 - Silicates.

Faceted Emerald (2021-03-30) by Marcílio GazzinelliMM Gerdau - Museu das Minas e do Metal

Emerald presenting emerald cutting style. This particular step cutting style with eight sides is very suitable for emeralds and because of that, it is named after them, but it is also used for other stones. Chemical composition: Be3Al2Si6O18 - Silicates.

Rough Opal (2021-03-30) by Andrea FerreiraMM Gerdau - Museu das Minas e do Metal

Noble opal, stone known by its play-of-colors, has its main brazilian deposits in the Pedro II town, in the Piauí state. The variety fire opal also occurs in some regions. Chemical composition: SiO2·nH2O - Silicates

Faceted Opal (2021-03-30) by Lucas D'AmbrosioMM Gerdau - Museu das Minas e do Metal

Step cut opal presenting little opalescence. Chemical composition: SiO2·nH2O - Silicates.

Rough Garnet (2021-03-30) by Marcílio GazzinelliMM Gerdau - Museu das Minas e do Metal

Garnet- Group of nesosilicates, normally whith spherical shapes, which can be found in many Brazilian states.The sample in the picture is an almandine in quatz from Planalto da Borborema in Paraíba state. Chemical composition: Fe2+3Al2(SiO4)3 - Silicates

Faceted Garnet (2021-03-30) by Lucas D'AmbrosioMM Gerdau - Museu das Minas e do Metal

Garnet with a dark red color, there is a light behind the stone in order to make a better color presentation. The stone presents an emerald cutting style. Chemical composition: Fe2+3Al2(SiO4)3 - Silicates

Rough Paraiba Tourmaline (2021-03-30) by Andrea FerreiraMM Gerdau - Museu das Minas e do Metal

Paraíba Tourmaline - Rare and valuable variety of cupriferous elbaite. It was first discovered in São José da Batalha town (Paraíba state). Its neon blue or electric neon hue is the most appreciated. This is one of the most expensive gems in the world. Chemical composition: Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH) - Silicates.

Rough Tourmaline (2021-03-30) by Andrea FerreiraMM Gerdau - Museu das Minas e do Metal

It is a mineral Supergroup with over 30 species and the main species extracted in Brazil is elbaite. The sample in the picture is a rough green elbaite from Distrito Barra do Salinas, Coronel Murta, MG. Chemical composition: Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH) - Silicates.

Faceted Tourmaline (2021-03-30) by Lucas D'AmbrosioMM Gerdau - Museu das Minas e do Metal

Three green elbaites cut in emerald style. Chemical composition: Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH) - Silicates.

Rough Aquamarine (2021-03-30) by Andrea FerreiraMM Gerdau - Museu das Minas e do Metal

Blue or greenish blue Beryl. It is from Marambaia (Minas Gerais state) the biggest gem quality aquamarine ever found (110,5 Kg). Other great specimens from this state even received names as Marta Rocha (33,9 kg) and Cachacinha (65 kg). Chemical composition: Be3Al2Si6O18 - Silicates.

Faceted Aquamarine (2021-03-30) by Lucas D'AmbrosioMM Gerdau - Museu das Minas e do Metal

Aquamarine beryl with emerald modified cut. Chemical composition: Be3Al2Si6O18 - Silicates.

Rough Euclase (2021-03-30) by Andrea FerreiraMM Gerdau - Museu das Minas e do Metal

The first described euclase was found in Ouro Preto’s surroundings (Minas Gerais state). It is relatively rare and it can present itself in the blue, green, yellow colors and colorless. The blue variety is the most appreciated. Chemical composition: BeAlSiO4(OH) - Silicates.

Rough and Faceded Imperial Topaz (2021-03-30) by Lucas D'AmbrosioMM Gerdau - Museu das Minas e do Metal

Imperial Topaz. The rarest topaz variety. It was first found in Ouro Preto when this city was yet named Vila Rica and was the capital of Minas Gerais state and up to the present this city is the reference in the production of this gem. Step cut Imperial topaz. Chemical composition: Al2SiO4F2.

Rough Rutilated Quartz (2021-03-30) by Andrea FerreiraMM Gerdau - Museu das Minas e do Metal

Brazil is a great producer of rutilated quartz with samples coming from the states Bahia and Minas Gerais. In the photo, it is possible to find an epitaxial growth of rutile on hematite forming a golden rutile star. Chemical composition: SiO2 - Silicates.

Rough Brazilianite (2021-03-30) by Andrea FerreiraMM Gerdau - Museu das Minas e do Metal

It was first found in Divino das Laranjeiras town (Minas Gerais state), and some years later it was named after the Brazilians. Despite not having high hardness, it is used as a gem. Chemical compostion: NaAl3(PO4)2(OH)4 - Phosphates.

Rough and faceded Kunzite (2021-03-30) by Lucas D'AmbrosioMM Gerdau - Museu das Minas e do Metal

Kunzite. Gemological pink variety of spodumene. This mineral was first discovered by the Brazilian mineralogist José Bonifácio de Andrada e Silva in Sweden. In Brazil, the state of Minas Gerais is a reference in this gem production. Step cut kunzite. Chemical composition: LiAlSi2O6 - Silicates.

Credits: Story

Realization: MM Gerdau - Museum of Mines and Metal
Sponsorship: Gerdau
Support: CBMM
Direction: Márcia Guimarães
Curatorship of Geosciences: Andrea Ferreira
Museology Coordination: Carlos Jotta
Communication Coordination: Paola Oliveira
Educational Coordination: Suely Monteiro
Curator of the “Precious Brazil: the wealth of gem-minerals” Exhibition: Andrea Ferreira, Carlos Jotta, Lucas D'Ambrósio, Márcia Guimarães, Mateus Nogueira, Paola Oliveira and Simone Silva Research: Andrea Ferreira
Texts: Andrea Ferreira, Carlos Jotta and Simone Silva
Texts Review: Paola Oliveira
Translation: Simone Silva
Photographs: Andrea Ferreira, Leonardo Miranda, Lucas D'Ambrosio e Marcílio Gazinelle

Credits: All media
The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.
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