The Clay Minerals Society Glossary of Clay Science, 2018 version Part Clay-Related Materials (Excluding exchanged phases) achlusite
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| partridgeite an obsolete term for the Fe-free variety of bixbyite, alpha-(Fe,Mn)2O3
pattersonite a poorly defined material, possibly interstratified biotite and vermiculite paucilithionite an obsolete term for trilithionite pearl-mica an obsolete term for margarite pecoraite the nickel analogue of chrysotile pelikanite an obsolete term for a kaolin, but probably a mixture, described from Kiev, Russia. Syn. kimolite (from Kimolos, Greece, also obsolete), cimolite pennantite the Mn-rich trioctahedral member of the chlorite group. See chlorite pennine an obsolete varietal term for clinochlore penninite a discredited trioctahedral Mg- and Si-rich chlorite, now referred to as clinochlore. See chlorite perlite see Part 1 of the Glossary. perraultite see astrophyllite group pimelite a kerolite-like phase where Ni > Mg pinguite an obsolete term for nontronite perlglimmer an obsolete term for margarite phengite a series name to describe potassium-rich dioctahedral micas between or close to the muscovite-aluminoceladonite join and the muscovite-celadonite join (i.e., Al,Mg,Fe-containing). philadelphite a poorly defined material, possibly a decomposition product of biotite and vermiculite phillipsite see zeolite phlogopite a trioctahedral member of the true mica group. The end-member formula is KMg3AlSi3O10(OH)2. Fe2+ for Mg substitution is common nearly to the Fe end member (annite). Mn and Ti and minor V and Cu substitution is less common. Octahedral vacancies are more prevalent in Fe -containing phlogopite. Phlogopite is defined as having <50% Fe substitution for Mg along the Mg/Fe join. When Fe and Mg content has not been determined, the series name, biotite, is appropriate. Tetrahedral Al substitution tends to be limited to <1.5 cations per formula unit (Fleet, 2003) and Fe3+ and Ti can occupy the tetrahedral site if there is a deficiency in Si. pholerite an obsolete and poorly defined term describing material from Fins, France, similar to kaolin but with apparently excess H2O pholidolite a poorly defined material, possibly phlogopite or saponite picrolite an obsolete varietal term for a fibrous to columnar form of green serpentine, often referring to antigorite. The original locality is from Taberg, Sweden, and this material was shown to be carlosturanite. The material from Bare Hills, Maryland, USA, was called baltimorite and is considered an obsolete term also. picrophengite an obsolete varietal term for magnesian muscovite pimelite not a valid mineral species, but is often used to describe Ni-rich, 2:1 layer silicates with additional structural H2O. Cf., kerolite pinite a poorly defined material, possibly a pseudomorph mostly of mica after cordierite, nepheline, or scapolite piotine an obsolete term for saponite plombièrite see tobermorite 14Å polianite The obsolete term "polianite" was once used to refer to crystalline pyrolusite, which was assumed to be a different species than earthy to “crusty” pyrolusite. poly-irvingite an obsolete varietal term for lepidolite polylithionite a trioctahedral member of the true mica group. The end-member formula is KLi2AlSi4O10F2. potash mica an obsolete term for muscovite potash margarite an obsolete varietal term for margarite pregrattite an obsolete term for paragonite preiswerkite a trioctahedral member of the true mica group. The end-member formula is NaMg2Al(Al2Si2)O10(OH)2. priderite see hollandite prochlorite a discredited name for an often iron-rich, but Si-poor chlorite protolithionite an obsolete varietal term for zinnwaldite, lithian annite, and lithian siderophyllite pseudobiotite a poorly defined material, possibly interstratified biotite and vermiculite or interlayer-deficient biotite pseudo-lussatine an obsolete name for opal, see opal pseudophite an obsolete term for a compact, massive chlorite that resembles serpentine pseudo-quartzine an obsolete name for opal or quartzine pseudosteatite an obsolete term for poorly defined material, impure halloysite pseudothuringite an obsolete term for low-Si chlorite psilomelane an obsolete manganese oxide name, now known as cryptomelane, see hollandite. Also, a term used to describe any massive, gray to black, hard, fine-grained manganese oxide material. Often, the latter material is romanechite. Cf., wad, romanechite pterolite a poorly defined material, possibly a decomposition product of hornblende consisting of mica and alkali pyroxene pycnochlorite a poorly defined material, found as infillings in cavities in basic igneous rocks, possibly an altered chlorite or an iron-rich clinochlore pycnophyllite an obsolete term for fine-grained muscovite or illite pyknophyllit an obsolete term for fine-grained muscovite or illite pyroaurite see hydrotalcite group pyrochroite Pyrochroite, Mn(OH)2, structurally forms sheets of Mn(OH)6 octahedra and is isostructural with brucite. The structure is hexagonal closest packed. Pyrochroite occurs in low-temperature hydrothermal environments. Cf., brucite pyrolusite see groutite pyrophyllite the dioctahedral member of the talc-pyrophyllite group. The ideal composition is Al2Si4O10(OH)2. Pyrophyllite forms as a prominent 1A polytype (where A = anorthic, older literature refers to this polytype as 1Tc) and a less prominent, poorly crystalline 2M polytype. The stacking of 2:1 layers in pyrophyllite (Lee and Guggenheim, 1981) is not constrained by an interlayer cation as in the micas, but is related to Si4+ to Si4+ repulsions across the vacant interlayer region. Thus Si tetrahedra between adjacent layers are shifted by ~a/3 so that there are no six-fold or twelve-fold interlayer sites available for interlayer cations, as in mica. Ferripyrophyllite is the ferric iron analogue of pyrophyllite. Pyrophyllite occurs in highly Al-rich metapelites, including metabauxites and metaquartzites, and under hydrothermal conditions. Cf., talc pyrosclerite an obsolete name for altered material, probably vermiculite pyrosmalite a modulated 1:1 layer silicate with a continuous, planar octahedral sheet and a general chemical composition of M2+8T6O15(OH,Cl)10. Pyrosmalite is the M = Mn, Fe series, manganpyrosmalite is M for Mn > Fe, and ferropyrosmalite is M for Fe > Mn. Friedelite is the Mn end member and a disordered (polytypic) equivalent of mcGillite. In addition, mcGillite has several additional polytypes. The pyrosmalite structure has an equal number of tetrahedra coordinating to two adjacent octahedra sheets via tetrahedral apical oxygen atoms (Kato and Takéuchi, 1983). Each tetrahedral sheet is composed of 4-, 6-, and 12-fold tetrahedral rings linked laterally, with half of the tetrahedra in the 4- and 12-fold rings inverted. Schallerite and nelenite are polymorphs and similar to friedelite, but apparently with As3O6 molecules within the 12-fold rings. Arsenite analogues of pyrosmalite-type minerals (T = As) occur: manganarsite (analogue manganpyrosmalite), and unnamed arsenite equivalents of schallerite and friedelite. Phase assemblages and occurrences are complex. Pyrosmalite occurs in greenschist facies manganiferous rocks. A near Fe-rich end member was reported from low-grade Fe- and Mn-rich sulfide deposits near Mt. Isa, Queensland, Australia. Friedelite occurs in low-grade metamorphic rocks and is Cl bearing. quartz Quartz, SiO2, is comprised of two chains, both spirals of SiO4 tetrahedra parallel to the c axis. In the alpha-quartz structure (low temperature form to 573 oC at 1 bar), these chains are kinked and the structure has trigonal symmetry. In the beta-quartz structure (high temperature form, above 574.3 oC), the chains expand (the tetrahedra are not twisted) and the symmetry is hexagonal with a more open structure than the alpha form. The beta form is non-quenchable and not found under ambient conditions. An intermediate phase between 573 - 574.3 oC is known to exist. Quartz is a common associated phase in clay, but generally forms grains larger than clay particles (about 0.2 - 0.4 micrometers) and therefore quartz particles can be removed by size separation. quartzine Quartzine is a rock term to describe a mixture of a fibrous [0001] variety of microcrystalline (length slow) quartz and moganite. Cf., chalcedony rabenglimmer an obsolete term for zinnwaldite raite a member of the palygorskite-sepiolite group with a composition of approximately Na3Mn3Ti0.25 (Si8O20) (OH)2. 10(H2O). See palygorskite-sepiolite group ramesdellite see groutite ranceite see birnessite rastolyte a poorly defined material, possibly an altered biotite or interlayer-deficient biotite rectorite a regular interstratification of dioctahedral mica-like layers and dioctahedral smectite-like layers in a ratio of 1:1 (Brown and Weir, 1963). The structure may be described more completely as pairs of dioctahedral 2:1 layers with alternate interlayers that are mica-like and montmorillonite-like. Mica-like layers may be paragonite-like and the smectite-like layers may be beidellitic. The non-swelling mica interlayers contain about 0.85 univalent cations per mica formula unit and the swelling interlayers about 0.35 univalent cations (e.g., Na, K, but divalent Ca is known also) per smectite formula unit (Bailey, 1982). In the older literature, the name “allevardite” has been used (Bailey, 1982), but the term rectorite has priority. redledgeite see hollandite reevesite see hydrotalcite group rensselaerite an obsolete, local term for talc pseudomorphic after pyroxene from northern New York state and Canada retinalite an obsolete term for a resinous, massive, yellow to green serpentine revdanskite a discredited name of a material that is primarily pimelite reyerite see reyerite group reyerite group Reyerite is comprised of a sheet of edge-sharing Ca octahedra with adjacent tetrahedral sheets of Si8O20 and a double tetrahedral sheet of Si14Al2O38, and an overall chemical composition of (Na,K)2Ca14Si22Al2O58(OH)8 . 6H2O (Merlino, 1988a). The tetrahedral sheets are formed from 6-fold rings of tetrahedra with some tetrahedra pointing up and some down. Na, K, and H2O occupy partially filled sites within the double tetrahedral sheet network. Truscottite, Ca14(Si24O58)(OH)8 . 2H2O, is similar to reyerite, but with alkali and aluminum generally absent, although a limited amount of K and Al can be present and the composition can approach reyerite. Gyrolite, Ca16Si24O60(OH)8 . (14+x)H2O, has a Ca octahedral sheet bounded by Si8O20 tetrahedral sheets as a unit (layer charge may vary from -4 to -5 depending on Al content) separated from other similar units by an interlayer of 2Ca + Na octahedra (Merlino, 1988b). Fedorite, K2(Ca5Na2)Si16O38(OH,F)2 . H2O, has a sheet of edge-sharing Ca octahedra with double tetrahedral sheets, Si16O38, on adjacent sides. Minehillite, (K,Na)2Ca28Zn5Al4Si40O112(OH)16, has a central edge sharing Ca octahedral sheet with a single tetrahedral sheet on one side (similar to reyerite), but a complex slab that differs from reyerite on the other. The structure of cairncrossite, Sr2Ca7-xNa2x(Si4O10)4(OH)2(H2O)15-x, where x is between 0 and 1, forms a unit consisting of edge-sharing Ca octahedral sheets with adjacent Si tetrahedral sheets. These units are cross linked by SrO8 polyhedra. The structure of orlymanite (chemical composition approximately Ca4Mn3Si8O20(OH)6 . 2H2O), which has not been determined, is believed related to reyerite. Synthetic (“K-phase”, “Z-phase”) phases with structural similarities to reyerite are known. Reyerite group minerals are potentially important in cements used to case geothermal wells where phases form at elevated temperatures and pressures in a steam-rich environment. rhombenglimmer an obsolete varietal term for phlogopite, biotite rhombic mica an obsolete varietal term for phlogopite, biotite ricolite an obsolete varietal term for a banded form of green serpentine riemannite a discredited name for allophane from Gräfental, Thuringia, Germany ripidolite a discredited name for an iron-rich, Si-poor chlorite. See chlorite riversideite see tobermorite romanechite The structure of romanechite, (Ba,H2O)2(Mn4+,Mn3+)5O10, forms large, rectangular-shaped tunnels bounded by double- and triple-chains of edge sharing MnO6 octahedra. The Mn3+ cations are located in the octahedra at the edges of the triple chains, and the Ba and H2O are located in the tunnels, often in a ratio of 1 to 2. Romanechite occurs in oxidized zones in Mn-rich ore deposits. roscoelite a dioctahedral member of the true mica group. The end-member formula is KV2▫AlSi3O10(OH)2. röttisite a discredited name for material primarily containing pimelite rubellan a poorly defined material, possibly altered biotite or interlayer-deficient biotite, and/or vermiculite rumpfite a poorly defined term, possibly for a Si-poor chlorite saliotite Saliotite is a regular interstratification (mixed layer) of cookeite-like and paragonite-like layers in a ratio of 1:1 (Goffé et al., 1994). The ideal chemical composition is Na0.5Li0.5Al3(Si3Al)O10(OH)5 and it occurs in high-pressure, low-temperature metamorphic rocks (estimated at 280-330 oC, 8 kbar) in Andalusia, Spain. Cf., interstratification sandbergite an obsolete term for barian muscovite saponite Saponite is ideally (M+x-y . nH2O)(Mg3-yR3+y )(Si4-xAlx)O10(OH)2 where M is the exchangeable cation in the interlayer (univalent example given here), R3+ are y trivalent cation substitutions in the octahedral site, x is the number of substitutions for Si by Al in the tetrahedral sites, and n is variable. Natural samples (Moore and Reynolds, 1997) may show < 0.66 Al tetrahedral atoms per asymmetric unit [O10(OH)2] to produce a large negative charge in the tetrahedral sheet which is balanced by positive charge in the octahedral sites (R3+ cations) and interlayer exchangeable (M) cations. Octahedral site vacancies may also occur (Newman and Brown, 1987). Suquet et al. (1975) determined that the two-layer hydrate structure (two planes of H2O) of a Na-saturated sample is C centered with a = 5.333, b = 9.233, c = 15.42 Å, β = 96.66 o. The sample approximates a Ia-2 polytype. The d(001) values of saponite commonly range from 13.5 (air dry) to 16.8 Å (ethylene glycol treatment). Dehydrated K-exchanged saponite shows a mica-like structure with stacking described as either a 1M or 3T structure. Saponite with a Mg-rich octahedral sheet is usually, but not limited to, a weathering product involving volcanic rocks (see Guggenheim, 2011 for a literature review of natural and synthetic saponite). Ferrian saponite (e.g., Kodama et al., 1988) with a composition of (M+0.61 . nH2O) (Mg1.39Fe3+0.85Al0.17Mn0.03) (Si3.49Al0.51) O10(OH)2 and ferrosaponite (Chukanov et al., 2003), (Ca0.31Na0.04K0.01 . 4H2O) (Fe2+1.54Mg0.85Fe3+0.45)Σ = 2.84 (Si2.87Al1.01Fe3+0.12) O9.67(OH)2.33, occur in a gabbro saprolite and as a hydrothermal mineral in basaltic pillow lavas, respectively. Cf., smectite sarospatakite an obsolete term for illite sauconite The Zn2+-rich trioctahedral smectite (Ross, 1946) with the ideal composition of (M+x . nH2O)Zn3(Si4-xAlx)O10(OH)2 where M is the exchangeable cation in the interlayer (univalent example given here), x is the number of substitutions for Si by Al in the tetrahedral sites, and n is variable. Zn content may vary commonly from 1.48 to 2.89 atoms per O10(OH)2, and the octahedral site may contain vacancies. Mg, Fe3+, and Al are known to replace Zn (Faust, 1951). scale stone an obsolete term for lepidolite schallerite see pyrosmalite schernikite an obsolete term for muscovite schrötterite an obsolete term for what is believed to be a mixture of opal and allophane schuchardite an obsolete term, probably a nickel-bearing chlorite schuppenstein an obsolete term for lepidolite seidozerite see astrophyllite group seladonite an obsolete term for celadonite sepiolite A member of the palygorskite-sepiolite group with a composition of approximately (Mg8-y-zR3+y☐z) (Si12-xR3+x) O30 (OH)4 (OH2)4 . R2+(x-y+2z)2 (H2O)8, where R are cations, ☐ are vacancies, and x, y, and z are compositional parameters. See palygorskite-sepiolite group sepiolite-palygorskite group see Part 1 of the Glossary sericite a poorly defined term, commonly used in the past to describe an optical microscopic fine-grained aggregate of mica-like phases serpentine see serpentine-kaolin group serpentine/chlorite (or serpentine-chlorite) a general term used to describe randomly interstratified layers (= “mixed layers”) of two types: 1:1 layers (i.e., serpentine-like, 7-Å spacing) and 2:1 layers + interlayer (i.e., chlorite-like, 14-Å spacing). The “random” (non-periodic) aspect is important because such a structure will not produce basal X-ray reflections expected by the Bragg equation. A non-periodic structure, i.e., a structure with random interstratifications, is not defined as a mineral (and cannot be given a mineral name). Serpentine-chlorite structures form most commonly under diagenetic conditions as authigenic material associated with pore-linings and fillings, peloids, and replacement phases. serpentine/kaolin see Part 1 of the Glossary seybertite an obsolete varietal term for clintonite shafranovskite a 2:1 hydrous phyllosilicate with continuous sheets of Mn and Na octahedra between two types of tetrahedral sheets. One sheet has isolated Si13(O,OH)37 islands whereas the other has similar islands with SiO3(OH) tetrahedra linkages between islands. The 2:1 layers are apparently not cross linked. The ideal chemical composition is K2Na3(Mn,Fe,Na)4[Si9(O,OH)27] (OH)2 . nH2O, with n ~ 2.33. Shafranovskite occurs in the pegmatites of the Khibiny and Lovozero alkaline complexes, Kola peninsula, Russia. sheridanite a discredited name for a trioctahedral Mg-rich (Fe-poor), Si-poor chlorite. See chlorite shilkinite an obsolete varietal term for ferroan muscovite, ferroan illite shirokshinite a trioctahedral member of the mica group characterized by Na occurring in the octahedral sheet in the M1 site. The ideal chemical composition is K(NaMg2)Si4O10F2. It is found in the apatite mine, Kukisvumchorr Mountain, Khibiny massif, Kola Peninsula, Russia, as a late hydrothermal phase in a small hyperalkaline pegmatite and it forms in the 1M polytype (Pekov et al., 2003). siderischer-fels-glimmer an obsolete term for lepidolite siderophyllite A trioctahedral member of the true mica group. The end-member formula is KFe2+2Al(Al2Si2)O10(OH)2. silica Silica refers to the chemistry only, SiO2, and not a specific structure or phase. Cf., silica, amorphous; cristobalite, tridymite, opal sinopite an obsolete term for an iron-rich red clay used as a pre-history ocher in the Black sea region sjögrenite see hydrotalcite group skolite an obsolete term for glauconite smectite The group name for the 2:1 phyllosilicate minerals with a net negative layer charge between approximately -0.2 and -0.6 per formula unit on the layer. A generalized formula is X0.3Y2-3Z4O10(OH)2 . nH2O, where X is the exchangeable cation (e.g., Ca/2, Na, K, Mg/2), Y is a small to medium size cation (e.g., Al, Cr3+, Fe2+, Fe3+, Li, Mg, Ni, Zn), Z = Si, Al, and n is a rational number, not necessarily an integer). Smectite is often characterized by solvating polar organic molecules into the interlayer causing pronounced swelling between the layers [perpendicular to the (001) plane]. Smectite is commonly referred to as a “swelling clay”, as is vermiculite. The rock term, bentonite, refers to a smectite-rich material. See further discussion under Part 1, smectite and obsolete terms: Wyoming-type, Otay-type, Chambers-type, Tatatila-type, beidellite-type (ideal and non-ideal), and non-ideal montmorillonite. Cf., bentonite, swelling clay, beidellite, hectorite, montmorillonite, nontronite, saponite, sauconite, stevensite, swinefordite, volkonskoite, yakhontovite soda mica an obsolete term for paragonite soda glauconite an obsolete varietal term for glauconite soda margarite an obsolete term for calcic paragonite, calcic ephesite Yüklə 428,36 Kb. Dostları ilə paylaş:
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