Mafic refers to the composition of igneous rocks that are rich in dark-colored minerals, primarily mafic minerals. Mafic minerals are those that contain a high proportion of iron and magnesium, such as olivine, pyroxene, and amphibole. These dark-colored minerals give mafic rocks their characteristic dark coloration. One of the key properties associated with mafic rocks is their relatively high specific gravity or density. This means that mafic rocks are generally heavier than other types of rocks. The specific gravity of mafic rocks can range from around 2.
Intermediate rocks are those that have compositions between mafic and silicic.
Intrusive rocks are classified on the proportion of major minerals in them, particularly the relative amounts of quartz, alkali-feldspar, and plagioclase. Intrusive rocks are classified on the proportion of major minerals in them, particularly the relative amounts of quartz, alkali-feldspar, and plagioclase.
The specific gravity of mafic rocks can range from around 2.7 to 3.3, which is higher than the specific gravity of most other common rock types.
Transformation of low-molecular-weight organic acids by microbial endoliths in subsurface mafic and ultramafic igneous rock
A growing body of work indicates that continental subsurface rocks host a substantial portion of the Earth's biosphere. However, the activities of microbial cells inhabiting pore spaces and microfractures in subsurface rocks remain underexplored. Here, we develop and optimize microcosm assays to detect organic acid transformation activities of cells residing in mafic to ultramafic igneous rocks. Application of this assay to gabbro core from the Stillwater Mine, Montana, USA, revealed maximal methane production from acetate at temperatures approximating that of the mine. Controls show that these activities are not due to contamination introduced during drilling, exhumation, or laboratory processing of the core. The assay was then applied to rocks cored from the Samail Ophiolite, Oman, which is undergoing low-temperature serpentinization. Production of (i) carbon dioxide from acetate and formate and (ii) methane from formate were detected in a dunite/harzburgite rock core interfacing pH 9.6 waters, and estimates of microbial activities were up to three orders of magnitude higher in the rock core pore space than in corresponding waters. The detection of endolithic microbial activities in igneous rocks has implications for life detection on other planetary bodies where similar rock types prevail, such as Mars, Europa and Enceladus.
© 2022 Society for Applied Microbiology and John Wiley & Sons Ltd.
The weight of mafic rocks is largely influenced by their mineral composition. The high content of iron and magnesium in mafic minerals contributes to their higher density. These minerals are generally denser than other common minerals found in rocks. For example, olivine, which is a common mafic mineral, has a specific gravity of around 3.2 to 4.3. The weight of mafic rocks can have important implications for various geological processes. For example, during volcanic eruptions, mafic magma, which is produced from the melting of mafic rocks in the Earth's mantle, tends to be denser and therefore less buoyant than felsic magma. This can result in the mafic magma being trapped at depth and forming intrusive igneous rocks, such as gabbro or diorite. Additionally, the weight of mafic rocks can affect their behavior during transportation and deposition. Due to their higher density, mafic rocks are less likely to be transported long distances by wind, water, or ice compared to lighter rocks. Instead, they tend to be deposited closer to their source, resulting in localized accumulations of mafic rocks in certain areas. Overall, the weight of mafic rocks is an important characteristic that reflects their mineral composition and has implications for various geological processes. The high density of mafic rocks is primarily due to the presence of iron and magnesium-rich minerals, making them heavier than other types of rocks..
Reviews for "The Significance of Mafic Minerals in Petrological Analysis"
1. John - 2 out of 5 stars - I found "The Weight of Mafic" to be incredibly slow-paced and unengaging. The story dragged on without any significant plot development, and the characters felt underdeveloped and uninteresting. I struggled to connect with any of them, and ultimately, I found myself frustrated and bored. The writing style lacked the depth and richness that I was hoping for, and overall, I was disappointed with this book.
2. Emily - 1 out of 5 stars - I really tried to like "The Weight of Mafic," but I just couldn't get into it. The storyline was confusing and disjointed, making it difficult to follow along. The author's use of metaphors and symbolism felt forced and overdone, leaving me feeling frustrated and disconnected. Additionally, the pacing was slow, and the lack of action or suspense made it a struggle to keep reading. Overall, this book was not for me, and I would not recommend it.
3. Sarah - 2 out of 5 stars - "The Weight of Mafic" had a lot of potential, but unfortunately, it fell flat for me. The writing style was overly descriptive, to the point where it felt like the author was trying too hard to impress rather than focusing on the story itself. The characters lacked depth and their actions often felt unbelievable. I found myself losing interest and skim-reading through parts of the book. While the concept was interesting, the execution left much to be desired, and I was left feeling disappointed and underwhelmed.