The large crystals are called phenocrysts and the fine-grained matrix is called the groundmass or matrix. Diamond and graphite are also native element minerals, both composed entirely of carbon. Bonding between sheets is relatively weak, and this accounts for the well-developed one-directional cleavage in micas (Figure \(\PageIndex{5}\)). Andesite is a fine crystalline intermediate extrusive rock. For silicate minerals, we group minerals based on their silicate structure into groups called: isolated, pair, ring, single chain, double chain, sheet, and framework silicates. What are some non silicate minerals? In fact, the ions that are common in silicate minerals have a wide range of sizes, as depicted in Figure 3.1.3. These dark ferromagnesian minerals are commonly found in gabbro, basalt, diorite, and often form the black specks in granite. The hardness and lack of cleavage in quartz result from the strong bonds characteristic of the silica tetrahedron. Cooling history is also related to changes that can occur to the composition of igneous rocks. Some igneous rocks have a mix of coarse-grained minerals surrounded by a matrix of fine-grained material in a texture called porphyritic. olivine Which of the following is a non-silicate mineral? 2. Ferromagnesian silicates tend to be more dense than non-ferromagnesian silicates. 1. 2.1 Minerals - Environmental Geology In muscovite mica, the only cations present are aluminum and potassium; hence it is a non-ferromagnesian silicate mineral. In pyroxene, the one divalent cation (2+) per tetrahedron balances that 2 charge. Olivine, pyroxene, amphibole,biotite, and garnet are all examples. *Some of the formulas, especially the more complicated ones, have been simplified. The three main feldspar minerals are potassium feldspar, (a.k.a. Micas and clays are common types of sheet silicates, also known as phyllosilicates. They are formed when magma exploits a weakness between these layers, shouldering them apart and squeezing between them. Polymers are chains, sheets, or three-dimensional structures, and are formed by multiple tetrahedra covalently bonded via their corner oxygen atoms. Silicate minerals are classified as being either ferromagnesian or non-ferromagnesian depending on whether or not they have iron (Fe) and/or magnesium (Mg) in their formula. { "2.01:_Electrons_Protons_Neutrons_and_Atoms" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "2.02:_Bonding_and_Lattices" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "2.03:_Mineral_Groups" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "2.04:_Silicate_Minerals" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "2.05:_Formation_of_Minerals" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "2.06:_Mineral_Properties" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "2.07:_Summary" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, { "00:_Front_Matter" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "01:_Introduction_to_Geology" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "02:_Minerals" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "03:_Intrusive_Igneous_Rocks" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "04:_Volcanism" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "05:_Weathering_and_Soil" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "06:_Sediments_and_Sedimentary_Rocks" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "07:_Metamorphism_and_Metamorphic_Rocks" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "08:_Measuring_Geological_Time" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "09:_Earths_Interior" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "10:_Plate_Tectonics" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "11:_Earthquakes" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "12:_Geological_Structures" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "13:_Streams_and_Floods" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "14:_Groundwater" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "15:_Mass_Wasting" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "16:_Glaciation" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "17:_Shorelines" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "18:_Geology_of_the_Oceans" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "19:_Climate_Change" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "20:_Geological_Resources" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "21:_Geological_History_of_Western_Canada" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "22:_The_Origin_of_Earth_and_the_Solar_System" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "zz:_Back_Matter" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, [ "article:topic", "showtoc:no", "license:ccby", "authorname:searle", "licenseversion:40", "source@https://opentextbc.ca/physicalgeology2ed", "program:bcc" ], https://geo.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fgeo.libretexts.org%2FBookshelves%2FGeology%2FPhysical_Geology_(Earle)%2F02%253A_Minerals%2F2.04%253A_Silicate_Minerals, \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}}}\) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\), source@https://opentextbc.ca/physicalgeology2ed, Micas, clay minerals, serpentine, chlorite, An angstrom is the unit commonly used for the expression of atomic-scale dimensions. Answered: (non-ferromagnesian) silicates with the | bartleby Two other similar arrangements of tetrahedra are close in structure to the neosilicates and grade toward the next group of minerals, the pyroxenes. 2.5 Formation of Minerals. Biotite mica can have iron and/or magnesium in it and that makes it a ferromagnesian silicate mineral (like olivine, pyroxene, and amphibole). What is considered a Ferromagnesian silicate? - Our Planet Today Choose all that apply. This should give you the ratio of Si to O in double-chain silicates (e.g., amphibole). In olivine, the 4 charge of each silica tetrahedron is balanced by two divalent (i.e., +2) iron or magnesium cations. The diagram below represents a single chain in a silicate mineral. This is called a coupled-substitution.. Not to be confused with a liquid solution, a solid solution occurs when two or more elements have similar properties and can freely substitute for each other in the same location in the crystal structure. The structure of the single-chain silicate pyroxene is shown on Figures 2.4.3 and 2.4.4. These are generally called the rock-forming minerals. 3.4 Non-silicate Minerals Figure 3.31: Hanksite, Na22K(SO4)9(CO3) . When lava is extruded onto the surface, or intruded into shallow fissures near the surface and cools, the resulting igneous rock is called extrusive or volcanic. Instead they are bonded to the iron and/or magnesium ions, in the configuration shown on Figure 3.1.2. 3.1 The Rock Cycle. There is even more sharing of oxygens between adjacent tetrahedra and hence fewer cations are needed to balance the charge of the silica-tetrahedra structure in sheet silicate minerals. A silicate mineral in which the silica tetrahedra are made up of sheets. Other sheet silicates include serpentine and chlorite, found in metamorphic rocks. A common member of the pyroxene family is augite, itself containing several solid solution series with a complex chemical formula (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6 that gives rise to a number of individual mineral names. The solid parts, called tephra, settle back to earth and cool into rocks with pyroclastic textures. Lava that cools extremely quickly may not form crystals at all, even microscopic ones. One theory is the overriding rock gets shouldered aside, displaced by the increased volume of magma. Batholiths and stocks are discordant intrusions that cut across and through surrounding country rock. This single-chain crystalline structure bonds with many elements, which can also freely substitute for each other. In mica minerals, the silica tetrahedra are arranged in continuous sheets. The intermediate-composition plagioclase feldspars are oligoclase (10% to 30% Ca), andesine (30% to 50% Ca), labradorite (50% to 70% Ca), and bytownite (70% to 90% Ca). Composition refers to the rocks specific mineralogy and chemical composition. Bonding between sheets is relatively weak, and this accounts for the well-developed one-directional cleavage in micas. a. Plagioclase Feldspars - solid solution series between anorthite (CaAl 2 Si 2 O 8) and albite (NaAlSi 3 O 8). These ions have similar ionic sizes, which allows many possible substitutions among them. Because each silicon ion is +4 and each oxygen ion is 2, the three oxygens (6) and the one silicon (+4) give a net charge of 2 for the single chain of silica tetrahedra. Mafic - Wikipedia Common mafic rocks include basalt, diabase and gabbro. 3.3 Crystallinity about Basalt. The oxidized form of an ion of iron (Fe3+). Accessibility StatementFor more information contact us atinfo@libretexts.org. The structure of the single-chain silicate pyroxene is shown on Figures 3.1.4 and 3.1.5. Rocks labeled as 'granite' in laymen applications can be several other rocks, including syenite, tonalite, and monzonite. Silica also refers to a chemical component of a rock and is expressed as % SiO2. A Dictionary of Earth Sciences. Sulfides are well known for being important ore minerals. Igneous rocks are common in the geologic record, but surprisingly, it is the intrusive rocks that are more common. Different mineral names are applied to compositions between these end members. Quartz contains only silica tetrahedra. The result is that the oxygen-to-silicon ratio is lower than in olivine (3:1 instead of 4:1), and the net charge per silicon atom is less (2 instead of 4), since fewer cations are necessary to balance that charge. Nonsilicate Mineral - an overview | ScienceDirect Topics A sheet silicate mineral (e.g., biotite). For each one, indicate whether or not it is a ferromagnesian silicate. Clays This problem is accounted for by corresponding substitution of Al3+ for Si4+. In addition to silica tetrahedra, feldspars include the cations aluminum, potassium, sodium, and calcium in various combinations. Table 2.1.5 Important Minerals; Types of Minerals: Examples: Silicate minerals of common rocks: plagioclase feldspar, potassium feldspar, quartz, mica, amphibole, pyroxene and olivine: Muscovite micas belong to the felsic silicate minerals. Quartz and feldspar are the two most abundant minerals in the continental crust. Plutons can have irregular shapes, but can often be somewhat round. This gives mica its characteristic property of easily cleaving into sheets. *Some of the formulas, especially the more complicated ones, have been simplified. Note how the mineral accommodates the substitution of Ca++ and Na+. A silicate mineral that does not contain iron or magnesium (e.g., feldsspar). Non-ferromagnesian Silicates are silicate minerals without substantial Fe and Mg in their crystalline structure. Other rarer elements with similar properties to iron or magnesium, like manganese (Mn), can substitute into the olivine crystalline structure in small amounts. Learn more about how Pressbooks supports open publishing practices. 7.3 Classification of Igneous Rocks - Physical Geology, First . Olivine can be either Mg2SiO4 or Fe2SiO4, or some combination of the two (Mg,Fe)2SiO4. In other words, pyroxene has one cation for each silica tetrahedron (e.g., MgSiO3) while olivine has two (e.g., Mg2SiO4). The silicon-oxygen tetrahedron (SiO4) consists of a single silicon atom at the center and four oxygen atoms located at the four corners of the tetrahedron. The names pyroxene, amphibole, mica, and feldspar can be confusing at first, as these are technically names of mineral families and not names of a specific mineral. In silicate minerals, these tetrahedra are arranged and linked together in a variety of ways, from single units to complex frameworks (Table 2.6). In quartz (SiO2), the silica tetrahedra are bonded in a perfect three-dimensional framework. The divalent cations of magnesium and iron are quite close in radius (0.73 versus 0.62 angstroms[1]). To give an example of how large these crystals can get, transparent cleavage sheets of pegmatitic muscovite mica were used as windows during the Middle Ages. In addition to silica tetrahedra, feldspars include the cations aluminum, potassium, sodium, and calcium in various combinations. A potassium-bearing non-ferromagnesian mica. Arndt, N. T. Chapter 1 Archean Komatiites. Nature rarely has sharp boundaries and the classification and naming of rocks often impose what appears to be sharp boundary names onto a continuous spectrum. The table below lists examples of oxides, sulphides, sulphates, halides, native elements and carbonates of economic value. There is no need for aluminum or any of the other cations such as sodium or potassium. These groups refer to differing amounts of silica, iron, and magnesium found in the minerals that make up the rocks. The simplest silicate structure, that of the mineral olivine, is composed of isolated tetrahedra bonded to iron and/or magnesium ions. Biotite mica has more iron and magnesium and is considered a ferromagnesian silicate mineral. The chemical formula is (Fe,Mg)2SiO4. Minerals - Introduction to Earth Science 3. Ferro means iron and magnesian refers to magnesium. The illustration of the crystalline structure of mica shows the corner O atoms bonded with K, Al, Mg, Fe, and Si atoms, forming polymerized sheets of linked tetrahedra, with an octahedral layer of Fe, Mg, or Al, between them. A silicate mineral in which the silica tetrahedra are combined within sheets. These include the clay minerals kaolinite, illite, and smectite, and although they are difficult to study because of their very small size, they are extremely important components of rocks and especially of soils. There are two types of feldspar, one containing potassium and abundant in felsic rocks of the continental crust, and the other with sodium and calcium abundant in the mafic rocks of oceanic crust. Mafic rocks often also contain calcium-rich varieties of plagioclase feldspar. Instead, these minerals aremade of other elements in other chemical arrangements. This should give you the ratio of Si to O in double-chain silicates (e.g., amphibole). Amphibole is even more permissive than pyroxene and its compositions can be very complex. Porphyritic texture indicates the magma body underwent a multi-stage cooling history, cooling slowly while deep under the surface and later rising to a shallower depth or the surface where it cooled more quickly. Count the number of tetrahedra versus the number of oxygen ions (yellow spheres). 2.1 Electrons, Protons, Neutrons, and Atoms, 4.5 Monitoring Volcanoes and Predicting Eruptions, 5.3 The Products of Weathering and Erosion, 6.3 Depositional Environments and Sedimentary Basins, 7.5 Contact Metamorphism and Hydrothermal Processes, 9.1 Understanding Earth through Seismology, 10.1 Alfred Wegener the Father of Plate Tectonics, 10.2 Global Geological Models of the Early 20th Century, 10.3 Geological Renaissance of the Mid-20th Century, 10.4 Plates, Plate Motions, and Plate-Boundary Processes, 11.5 Forecasting Earthquakes and Minimizing Damage and Casualties, 15.1 Factors That Control Slope Stability, 15.3 Preventing, Delaying, Monitoring, and Mitigating Mass Wasting, 21.2 Western Canada during the Precambrian, Chapter 22 The Origin of Earth and the Solar System, Karla Panchuk, Department of Geological Sciences, University of Saskatchewan, 22.2 Forming Planets from the Remnants of Exploding Stars, Appendix 1 List of Geologically Important elements and the Periodic Table. This page titled 4.1: Classification of Igneous Rocks is shared under a CC BY-NC-SA license and was authored, remixed, and/or curated by Chris Johnson, Matthew D. Affolter, Paul Inkenbrandt, & Cam Mosher (OpenGeology) . A ferromagnesian sheet silicate mineral, typically present as fine crystals and forming from the low-temperature metamorphism of mafic rock. Basalt is the main rock which is formed at mid-ocean ridges, and is therefore the most common rock on the Earths surface, making up the entirety of the ocean floor (except where covered by sediment). As already noted, the 2 ions of iron and magnesium are similar in size (although not quite the same). Thats why pyroxenes can have iron (radius 0.63 ) or magnesium (radius 0.72 ) or calcium (radius 1.00 ) cations (see Figure 3.1.3 above). Amphibole is even more permissive than pyroxene and its compositions can be very complex. For example, it is not known what happens to the pre-existing country rock as the diapir intrudes. A fine-grained sheet silicate mineral that can accept water molecules into interlayer spaces, resulting is swelling. Two frequently found micas are dark-colored biotite, frequently found in granite, and light-colored muscovite, found in the metamorphic rock called schist. The three main feldspar minerals are potassium feldspar, (a.k.a. Silicate Minerals Types & Examples | What are Silicate Minerals Because of this, dikes are often vertical or at an angle relative to the pre-existing rock layers that they intersect. As weve seen, its called a tetrahedron because planes drawn through the oxygen atoms form a shape with 4 surfaces (Figure \(\PageIndex{4}\)). In some cases, extrusive lava cools so rapidly it does not develop crystals at all. Extrusive igneous rocks have a fine-grained or aphanitic texture, in which the grains are too small to see with the unaided eye. Chapter 6 Sediments and Sedimentary Rocks, Chapter 7 Metamorphism and Metamorphic Rocks, Chapter 21 Geological History of Western Canada, Creative Commons Attribution 4.0 International License, Micas, clay minerals, serpentine, chlorite. The building block of all of these minerals is the silica tetrahedron, a combination of four oxygen atoms and one silicon atom. Note that iron can exist as both a +2 ion (if it loses two electrons during ionization) or a +3 ion (if it loses three). The Van der Waals bonds are weak compared to the bonds within the sheets, allowing the sandwiches to be separated along the potassium layers. Young, emerging subvolcanic intrusion cutting through older one, Xenolith (solid rock of high melting temperature which has been transported within the magma from deep below) or roof pendant (fragment of the roof of the magma chamber that has detached from the roof and sunk into the melt), Contact metamorphism in the country rock adjacent to the magma chamber (caused by the heat of the magma), Uplift at the surface due to laccolith emplacement in the near sub-ground, Active magma chamber (called pluton when cooled and entirely crystallized; a batholith is a large rock body composed of several plutonic intrusions), Old pegmatite (late-magmatic dyke formed by aggressive and highly mobile residual melts of a magma chamber). Micas contain mostly silica, aluminum, and potassium. All magmas contain gases dissolved in a solution called volatiles. Another feldspar is plagioclase with the formula (Ca,Na)AlSi3O8, the solid solution (Ca,Na) indicating a series of minerals, one end of the series with calcium CaAl2Si2O8, called anorthite, and the other end with sodium NaAlSi3O8, called albite. For example, it can also be written more exactly as AX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2. If you are doing this in a classroom, try joining your tetrahedron with others into pairs, rings, single and double chains, sheets, and even three-dimensional frameworks. For each one, indicate whether or not it is a ferromagnesian silicate. One angstrom is 1010 m or 0.0000000001 m. The symbol for an angstrom is . When volcanoes erupt explosively, vast amounts of lava, rock, ash, and gases are thrown into the atmosphere. Because each silicon ion is +4 and each oxygen ion is 2, the three oxygens (6) and the one silicon (+4) give a net charge of 2 for the single chain of silica tetrahedra. Basalt and gabbro are the extrusive and intrusive names for mafic igneous rocks, and peridotite is ultramafic, with komatiite as the fine-grained extrusive equivalent. Since the silicon ion has a charge of +4 and each of the four oxygen ions has a charge of 2, the silica tetrahedron has a net charge of 4. Note that iron can exist as both a +2 ion (if it loses two electrons during ionization) or a +3 ion (if it loses three). ferromagnesian minerals Silicate minerals in which cations of iron and magnesium form essential chemical components. It is characteristically green when not weathered. Each tetrahedron has one silicon ion so this should give you the ratio of Si to O in single-chain silicates (e.g., pyroxene). If you are doing this in a classroom, try joining your tetrahedron with others into pairs, rings, single and double chains, sheets, and even three-dimensional frameworks. Another variation are the cyclosilicates, which as the name suggests, consist of tetrahedral rings, and include gemstones such as beryl, emerald, aquamarine, and tourmaline. Glazner, A. F., Bartley, J. M., Coleman, D. S., Gray, W. & Taylor, R. Z. Ferromagnesian Silicates are silicates with iron (Fe) and/or magnesium (Mg) in their structure. The silicon ion is much smaller than the oxygen ions (see the figures) and fits into a small space in the center of the four large oxygen ions, see if the top ball is removed (as shown in the figure to the right). non-ferromagnesian minerals they don't contain any iron or magnesium. Some example minerals are: 3-member single ring Benitoite - BaTi (Si3O9) 4-member single ring Papagoite - CaCuAlSi 2O 6(OH) 3. Feldspars are mostly silica with aluminum, potassium, sodium, and calcium. The silica chains are bonded together into the crystal structures by metal cations. Want to create or adapt books like this? The slow cooling process allows crystals to grow large, giving the intrusive igneous rock a coarse-grained or phaneritic texture. Extrusive rocks, because of their small crystals and glass, are less durable. 2. Sills are another type of intrusive structure. In addition to silica tetrahedra, feldspars include the cations aluminum, potassium, sodium, and calcium in various combinations. 3.1 Silicate Mineral Groups - A Practical Guide to Introductory Geology In muscovite mica, the only cations present are aluminum and potassium; hence it is a non-ferromagnesian silicate mineral. Accessibility StatementFor more information contact us atinfo@libretexts.org. Quartz contains only silica tetrahedra.