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The rocks studied in the present work are known commercially as White Fuji, Capuccino Fuji and Golden Fuji. They come from the same mining front located in the municipality of Pedra Lavrada/PB. They have a similar mineral composition, consisting mainly of quartz, plagioclase, muscovite, microcline and garnet with modal composition between 5% and 34% and accessory minerals, with a modal composition of less than 5%, especially sericite, biotite and opaque. Petrographically correspond to pegmatites with isotropic structure, mineral granulation ranging from medium to very coarse, high degree of mineral microcracking, incipient to moderate mineral alteration and predominant concave-convex mineral contacts. The values obtained for the physical-mechanical properties indicate that the pegmatites investigated can be used as ornamental and coating rock, however, reservations regarding the use of the White Fuji pegmatite are required, as a function of their performance in the porosity, water absorption, uniaxial compressive strength and flexural strength exhibit values lower than the limits established by current standards. The results obtained in the radon exhalation of the studied rocks are considered high: White pegmatite (215,0 Bq/m 3 ), Capuccino (176,3 Bq/m 3 ) and Golden (156,0 Bq/m 3 ). The results for radon gas exhalation efficiency demonstrate that the amount of 222 Rn effectively emanated in the rocks is small relative to the total amount of 222 Rn generated. The simulation for indoor environments shows that the dosimetric values obtained for White pegmatite were 0,88 pCi/L; 0,73 pCi/L for Cappuccino pegmatite and 0,64 pCi/L for Golden pegmatite revealing values below the dosimetric limit suggested by the United States Environmental Protection Agency.

São estudadas as rochas ornamentais Butterfly Beige, Butterfly Gold e Butterfly Green correspondentes a quartzo sienitos com hiperstênio que são exploradas em Barra de São Francisco-Espírito Santo, Brasil. O objetivo é analisar os efeitos estéticos, bem como quantificá-los, depois de submetidas à exposição de temperaturas elevadas a partir de análises comparativas das imagens, das cores e das respectivas características petrográficas. Os valores para os coeficientes de correlação (r) entre as rochas, já nos primeiros 200ºC, mostram descaracterizações moderadas, sendo as rochas bastante afetadas pela temperatura. As alterações causadas pela ciclagem térmica somada à umidade aceleram o processo de oxidação do Fe. Além disso, por histerese, a ciclagem implica a geração de microfissuras e o alargamento dos planos de clivagem dos minerais, bem como ofusca os contatos entre eles, facilitando a percolação de fluidos (água) e aumentando o grau de oxidação do Fe ao mesmo tempo em que facilita a disseminação do Fe(OH)2. Frente aos resultados obtidos, sugere-se que as rochas estudadas (principalmente a variedade Green) sejam utilizadas em revestimentos de ambientes internos e que fontes de calor, como o sol, em revestimentos externos, podem acelerar o processo de modificação das cores em função da presença de minerais ferro-magnesianos e, principalmente, do Fe (OH)2 passíveis de oxidação

The Granja Granulite Complex (GGC) exposed in the Médio Coreaú Domain (NW Ceará, Brasil) consists mainly of garnet and sillimanite migmatitic paragneisses enclosing discontinuous lenses of mafic granulites and enderbites. According to the published geochronological data, this high-grade metamorphic belt represents a segment of the Paleoproterozoic basement intensely reworked during the Brasiliano / Pan-African Orogeny in the Neoproterozoic (600 Ma). The Granja paragneisses are strongly foliated rocks characterized by the alternance of dark garnet-biotite-sillimanite-rich layers and millimeter-thick leucocratic quartz-feldspathic bands, interpreted as indicative of incipient melting. As melt contents increase, layer-parallel leucosomes become thicker and a well-developed stromatic layering is defined. Both the gneissic and stromatic fabrics are strongly overprinted by a penetrative mylonitic foliation correlated to the last reactivation of the dextral NE-SW trending Granja Shear Zone (GCZ) that cuts across the studied area. Mineral assemblages and microstructures indicate that these rocks were affected by granulite-facies metamorphism and anatexis followed by decompression and cooling. In order to constrain the protolith composition of the Granja paragneisses, twelve whole-rock samples from the parts of the migmatitic paragneisses that appear to have undergone little or no melt extraction were analysed for major and trace elements. In the classification diagram of Herron (1988), the samples plot in the transition between the greywacke and the pelite fields, suggesting that the pre-metamorphic sequence was dominantly composed by shales and immature clastic sediments (greywackes). Their chondrite normalized REE patterns show a moderate LREE enrichment (LaN/YbN = 9.46–15.50), flat HREE profiles and negative Eu anomalies (Eu/Eu* = 0.63–0.82), closely resembling those of PAAS (Post-Archean average Australian Shale) and Early Proterozoic Greywackes. Geochemical data also suggest that the precursor sediments of the Granja paragneisses derived from source areas of felsic to intermediate composition and were deposited in a tectonically active continental margin / continental island arc setting. El Complejo Granulítico de Granja (GGC), expuesto en el Dominio Medio Coreaú (NW del Estado de Ceará, Brasil), está constituido predominantemente por paragneises granatíferos con silimanita en cuyo seno se intercalan cuerpos lenticulares, discontinuos, de granulitas máficas y enderbitas. De acuerdo con los datos geocronológicos publicados, este terreno metamórfico de alto grado representa un segmento de un basamento Paleoproterozoico que fue intensamente retrabajado en el Neoproterozoico, durante la Orogénesis Brasiliense / Panafricana (600 Ma). Los paragneises de Granja son rocas con una fuerte foliación, caracterizadas por la alternancia de niveles oscuros, ricos en granate-biotita-silimanita, y bandas milimétricas leucocráticas cuarzo-feldespáticas interpretadas como resultado de fusión incipiente. Con el incremento del componente fundido, aumenta el espesor de los leucosomas concordantes y las rocas adquieren un aspecto estromático. A estas estructuras se superpone una foliación milonítica asociada a la última reactivación de la Zona de Cizalla de Granja, un accidente con dirección NE-SW y movimiento dextral que atraviesa la zona estudiada. Las asociaciones minerales y las texturas de reacción indican que después de alcanzar las condiciones de fusión parcial en la facies granulítica, las rocas sufrieron descompresión y enfriamiento. Con el fin de caracterizar la composición de los protolitos de los paragneises de Granja, se analizaron los elementos mayores y tierras raras de doce muestras de aquellas partes de los paragneises migmatíticos en los que la extracción de fundido parece haber sido nula o muy limitada. En el diagrama de clasificación de Herron (1988), las muestras se sitúan en la transición entre los campos de las grauvacas y pelitas, sugiriendo que en la secuencia pre-metamórfica dominaban sedimentos arcillosos y sedimentos clásticos poco maduros (grauvacas). Los patrones de tierras raras normalizados a condrita muestran un moderado enriquecimiento en las tierras raras ligeras (LaN/YbN = 9.46–15.50), perfiles planos en tierras raras pesadas y anomalías negativas de Eu (Eu/Eu* = 0.63–0.82), con pautas muy próximas tanto a las del PAAS (Post-Archean average Australian Shale) como a las del EP GREY (Early Proterozoic Greywackes). Los datos geoquímicos sugieren también que los sedimentos precursores de los paragneises de Granja tuvieron su origen en un área fuente con composición félsica a intermedia y fueron acumulados en un ambiente de margen continental activo / arco insular continental.