Micas (/ ˈmaɪkəz / MY-kəz) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into fragile elastic plates. This characteristic is described as perfect basal cleavage.

2025年3月2日 · Mica, any of a group of hydrous potassium, aluminum silicate minerals. It is a type of phyllosilicate, exhibiting a two-dimensional sheet or layer structure. Among the principal rock-forming minerals, micas are found in all three major rock varieties—igneous, sedimentary, and metamorphic.

Mica, which is essentially a compound of silicate minerals, is comprised of closely related materials that have perfect basal cleavage. They belong to the category of principal rock-forming minerals and are found in various categories like sedimentary, igneous, and metamorphic.

2023年4月23日 · Among the most important rock-forming minerals, micas are located in all 3 foremost rock types—igneous, sedimentary, and metamorphic. Chemically, micas can be given the general formula. X2Y4–6Z8O20 (OH, F)4, in which. Z is …

Mica is a mineral name given to a group of minerals that are physically and chemically similar. They are all silicate minerals, known as sheet silicates because they form in distinct layers. Micas are fairly light and relatively soft, and the sheets and flakes of mica are flexible.

2024年1月19日 · Mica refers to a group of silicate minerals renowned for their remarkable ability to be split into thin, elastic sheets. This attribute, known as perfect basal cleavage, sets mica apart in...

2017年8月31日 · Two micas, biotite, and muscovite, are so common that they are considered rock-forming minerals. The rest are relatively uncommon, but phlogopite is the most likely of these to be seen in the field. Rock shops overwhelmingly …

2025年3月2日 · In most rocks, micas occur as irregular tabular masses or thin plates (flakes), which in some instances appear bent. Although some mica grains are extremely small, all except those constituting sericitic masses have characteristic shiny cleavage surfaces. Glauconite is formed in marine environments. It can be found on seafloors where clastic ...

Mica is found in igneous, metamorphic, and sedimentary rocks, making it a common mineral in various geological environments. For rockhounds, mica is a popular mineral to collect due to its distinctive layered structure and ability to cleave into thin, flexible sheets.

Understanding how mica manifests in different rock types can provide critical insights into the geological history and processes that shaped those rocks. This section will explore mica's occurrence primarily in three rock categories: igneous, metamorphic, and sedimentary.