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Minerals, rocks, discontinuities and rock mass
Published in Ömer Aydan, Rock Mechanics and Rock Engineering, 2019
Sheets of tetrahedra are building blocks. Aluminum is also involved in these sheet structures, which are charge-balanced by the cations Mg, Na and K. They are divided into the muscovite and biotite groups. Muscovite is transparent and resistant to weathering. Biotite is characterized by shades of brown to black. They are commonly found in igneous and metamorphic rocks.
Rock Forming Minerals
Published in Aurèle Parriaux, Geology, 2018
Biotite (or “black mica”) is a ferromagnesian mica, black or smoky brown in color, with vitreous luster that is pearly on the cleavage (Fig. 5.22); its hardness ranges from 2.5 to 3 and its density from 2.8 · 103 kg/m3 to 3.2 · 103 kg/m3.
Rock Forming Minerals
Published in Aurèle Parriaux, Geology, 2018
Biotite (or “black mica”) is a ferromagnesian mica, black or smoky brown in color, with vitreous luster that is pearly on the cleavage (Fig. 5.22); its hardness ranges from 2.5 to 3 and its density from 2.8 · 103 kg/m3 to 3.2 · 103 kg/m3.
Multiscale Fire Damage Assessment of Historical Stone Trabeated Hypostyle Halls
Published in International Journal of Architectural Heritage, 2023
Swathy Manohar, Karpagam Bala, Shivangi Shukla, K. Mohammed Haneefa, Manu Santhanam, Arun Menon
Images of samples with Minor, Major and Extreme fire damage showed the presence of ferric oxide, which are the bright shattered particles whose quantity increased in samples with increasing fire damage (Figures 11,12 and14). The SEM images revealed the occurrence of innumerable fissures on surfaces of the mineral grains. The ferric oxidation starts at temperatures around 600°C, for the Fe from mafic minerals like biotite and hornblende (Sippel et al. 2007). Ferric oxides were seen to be most abundant near the surfaces of biotite, especially in extremely fire-affected samples (Figure 15). Biotite is the dark mica that forms flat, sheet-like crystals that cleave into smooth flakes. Corroborating the colour change trend in the thin section petrography, the SEM images of samples with a minor, major and extreme fire damage indicate that the iron oxidation was more prominent with increasing damage.
Titania-silica Composite with Photocatalytic Properties and Its Application on Brazilian Granite and Sandstone
Published in International Journal of Architectural Heritage, 2023
Danielle Grossi, Dolores Ribeiro Ricci Lazar, Eliane Aparecida Del Lama, Valter Ussui
Itaquera granite has a light grey colour (Figure 2A and 2B), slight foliation, fine crystal size (0.2–2 mm), and very low porosity (0.5%) (Gimenez 2018). It has a low anisotropy due to its only slightly oriented structure (Del Lama et al. 2015; Gimenez 2018). The mineralogy is composed of oligoclase, microcline, quartz, and biotite (Figure 2C and 2D). Oligoclase (38%) occurs as subtabular crystals, many of them zoned, with well-developed saussuritisation and epidotisation processes (Figure 2E and 2F). Microcline (33%) has tartan twinning and some crystals are perthitic. Quartz (18%) shows recrystallisation and strong wavy extinction. Biotite has a green to brownish-green colour and occurs as anhedral aggregates and subtabular crystals. In general, the crystals are corroded. Titanite (1%) and traces of zircon, apatite, and opaque minerals are present as accessory minerals, with epidote (1%) and traces of chlorite, sericite, and carbonate as secondary minerals. Centimetre-scale enclaves of biotite are common (Figure 2B). Its mineral composition indicates a hydrothermal alteration because of the wavy extinction and recrystallisation of quartz, curved twin lamellae of plagioclase, curved crystals of biotite, the relative abundance of epidote (Figure 2F), and plagioclase saussuritisation (Del Lama, Dehira, and Reys 2009). It is classified as a biotite monzogranite.
Investigation on the morphological and mineralogical properties of coarse aggregates under VSI crushing operation
Published in International Journal of Pavement Engineering, 2021
Chonghui Wang, Hainian Wang, Markus Oeser, Mohd Rosli Mohd Hasan
The granite aggregates, originated from Fujian province in China, were chosen for this study, as depicted in Figure 7, since they are commonly used for construction materials in coastal areas in southern China, and also some areas in the US for pavement engineering (Wang 2017). The mineralogical examination of the granite aggregates was applied through X-ray diffraction analysis, which revealed that this rock consists dominantly of quartz, feldspars (plagioclase), and biotite. These minerals generally have well-developed crystal faces (Kane et al.2013). Additionally, quartz and feldspars particles are relatively hard, exhibiting a Moh’s hardness value of 7 and 6, respectively. In contrast, biotite is relatively softer with a Moh’s hardness value between 2 and 3.