Lizardite

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Lizardite
Lizardit.jpg
General
Category Mineral
Formula
(repeating unit)
Mg3(Si2O5)(OH)4 [1]
IMA symbol Lz [2]
Strunz classification 9.ED.15
Dana classification 71.01.2b.02
Crystal system Trigonal
Identification
ColorGreen, brown, light yellow to white
Mohs scale hardness2.5
Luster Resinous, waxy, greasy
Streak White
Specific gravity 2.55

Lizardite is a mineral from the serpentine subgroup [3] with formula Mg3(Si2O5)(OH)4, and the most common type of mineral in the subgroup. [4] It is also a member of the kaolinite-serpentine group. [5]

Contents

Lizardite may form a solid-solution series with the nickel-bearing népouite (pure end-member: Ni3(Si2O5)(OH)4). Intermediate compositions (Mg,Ni)3(Si2O5)(OH)4 are possible, with varying proportions of magnesium and nickel. [6] However, the lizardite end-member is much more common than pure népouite, a relatively rare mineral most often formed by the alteration of ultramafic rocks.

Extremely fine-grained, scaly lizardite (also called orthoantigorite) comprises much of the serpentine present in serpentine marbles. It is triclinic, has one direction of perfect cleavage, and may be white, yellow or green. Lizardite is translucent and soft, and may be pseudomorphous after enstatite, olivine or pyroxene, in which case the name bastite is sometimes applied. Bastite may have a silky lustre. [1]

Name

Lizardite was named by Eric James William Whittaker and Jack Zussman in 1955 after the place it was first reported, the Lizard Peninsula, (from the Cornish : An Lysardh) in southern Cornwall, England, United Kingdom.

Scyelite is a synonym of lizardite. [1]

Characteristics

Chemistry

Antigorite and lizardite commonly coexist metastably; [7] :24 lizardite may also be able to turn into antigorite at over 350 degrees. [8] :712

Lizardite contains H2O in excess of the nominal formula, as does chrysotile. It has a high amount of Fe2O3 and a low amount of FeO. [9] :8

One study found that lizardite has a high amount of SiO2 and a low amount of Al2O3. [10] :193

Formation

Lizardite is commonly a result from the hydrothermal metamorphism or retrograde metamorphism of mafic minerals such as olivine, pyroxene or amphibole, in ultrabasic rocks. [11]

Occurrence

Geological occurrence

Lizardite is commonly found in ophiolite [12] and is often intergrown with brucite. [9] :8 It is also found with magnetite [11] and the other serpentine minerals. [13] :118–119

Locations found

Canada

As of 1989, only a single specimen of lizardite had been found in Mont-Saint-Hilaire, Quebec where it may occur in altered pegmatites. [14] :184

United States

Lizardite can be found in the United States. [15] In Pennsylvania It was discovered in the 1960s. [16] :55 With it being the most abundant mineral in Nottingham County Park. [17]

In Minnesota it can be found on the north shore of Lake Superior. [1]

In Montana, the Stillwater igneous complex is a prominent location for the mineral. [15]

United Kingdom

Lizardite has a type locality at Lizard Peninsula, Cornwall, in the United Kingdom. [1]

Scotland is a notable source of lizardite. [18] Lizardite has been reported in Wales. At Holy Island, Anglesey lizardite has been found to be associated with antigorite. [11]

South Africa

In the Frank Smith mine located in South Africa, lizardite was the dominant serpentine mineral. [10] :212

Orange lizardite has been found at the Wessels mine. [19]

Other

It can also be found in Japan, Italy, and Australia. [20]

Related Research Articles

<span class="mw-page-title-main">Gabbro</span> Coarse-grained mafic intrusive rock

Gabbro is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is chemically equivalent to rapid-cooling, fine-grained basalt. Much of the Earth's oceanic crust is made of gabbro, formed at mid-ocean ridges. Gabbro is also found as plutons associated with continental volcanism. Due to its variant nature, the term gabbro may be applied loosely to a wide range of intrusive rocks, many of which are merely "gabbroic". By rough analogy, gabbro is to basalt as granite is to rhyolite.

<span class="mw-page-title-main">Mineral</span> Crystalline chemical element or compound formed by geologic processes

In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.

<span class="mw-page-title-main">Peridot</span> Green gem-quality mineral

Peridot, sometimes called chrysolite, is a yellowish-green transparent variety of olivine. Peridot is one of the few gemstones that occur in only one color.

<span class="mw-page-title-main">Augite</span> Common rock-forming pyroxene mineral

Augite, also known as Augurite, is a common rock-forming pyroxene mineral with formula (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6. The crystals are monoclinic and prismatic. Augite has two prominent cleavages, meeting at angles near 90 degrees.

<span class="mw-page-title-main">Serpentine subgroup</span> Group of phyllosilicate minerals

Serpentine subgroup are greenish, brownish, or spotted minerals commonly found in serpentinite. They are used as a source of magnesium and asbestos, and as decorative stone. The name comes from the greenish color and smooth or scaly appearance from the Latin serpentinus, meaning "serpent rock".

<span class="mw-page-title-main">Peridotite</span> Coarse-grained ultramafic igneous rock type

Peridotite ( PERR-ih-doh-tyte, pə-RID-ə-) is a dense, coarse-grained igneous rock consisting mostly of the silicate minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica. It is high in magnesium (Mg2+), reflecting the high proportions of magnesium-rich olivine, with appreciable iron. Peridotite is derived from Earth's mantle, either as solid blocks and fragments, or as crystals accumulated from magmas that formed in the mantle. The compositions of peridotites from these layered igneous complexes vary widely, reflecting the relative proportions of pyroxenes, chromite, plagioclase, and amphibole.

<span class="mw-page-title-main">Garnierite</span> Nickel layer silicate

Garnierite is a general name for a green nickel ore which is found in pockets and veins within weathered and serpentinized ultramafic rocks. It forms by lateritic weathering of ultramafic rocks and occurs in many nickel laterite deposits in the world. It is an important nickel ore, having a large weight percent NiO. As garnierite is not a valid mineral name according to the Commission on New Minerals, Nomenclature and Classification (CNMNC), no definite composition or formula has been universally adopted. Some of the proposed compositions are all hydrous Ni-Mg silicates, a general name for the Ni-Mg hydrosilicates which usually occur as an intimate mixture and commonly includes two or more of the following minerals: serpentine, talc, sepiolite, smectite, or chlorite, and Ni-Mg silicates, with or without alumina, that have x-ray diffraction patterns typical of serpentine, talc, sepiolite, chlorite, vermiculite or some mixture of them all.

<span class="mw-page-title-main">Forsterite</span> Magnesium end-member of olivine, a nesosilicate mineral

Forsterite (Mg2SiO4; commonly abbreviated as Fo; also known as white olivine) is the magnesium-rich end-member of the olivine solid solution series. It is isomorphous with the iron-rich end-member, fayalite. Forsterite crystallizes in the orthorhombic system (space group Pbnm) with cell parameters a 4.75 Å (0.475 nm), b 10.20 Å (1.020 nm) and c 5.98 Å (0.598 nm).

<span class="mw-page-title-main">Silicate mineral</span> Rock-forming minerals with predominantly silicate anions

Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust.

<span class="mw-page-title-main">Cummingtonite</span> Silicate mineral

Cummingtonite is a metamorphic amphibole with the chemical composition (Mg,Fe2+
)
2
(Mg,Fe2+
)
5
Si
8
O
22
(OH)
2
, magnesium iron silicate hydroxide.

<span class="mw-page-title-main">Serpentinite</span> Rock formed by hydration and metamorphic transformation of olivine

Serpentinite is a metamorphic rock composed predominantly of one or more serpentine group minerals formed by near to complete serpentinization of mafic to ultramafic rocks. Its name originated from the similarity of the texture of the rock to that of the skin of a snake. Serpentinite has been called serpentine or serpentine rock, particularly in older geological texts and in wider cultural settings.

<span class="mw-page-title-main">Serpentinization</span> Formation of serpentinite by hydration and metamorphic transformation of olivine

Serpentinization is a hydration and metamorphic transformation of ferromagnesian minerals, such as olivine and pyroxene, in mafic and ultramafic rock to produce serpentinite. Minerals formed by serpentinization include the serpentine group minerals, brucite, talc, Ni-Fe alloys, and magnetite. The mineral alteration is particularly important at the sea floor at tectonic plate boundaries.

<span class="mw-page-title-main">Komatiite</span> Magnesium-rich igneous rock

Komatiite is a type of ultramafic mantle-derived volcanic rock defined as having crystallised from a lava of at least 18 wt% magnesium oxide (MgO). It is classified as a 'picritic rock'. Komatiites have low silicon, potassium and aluminium, and high to extremely high magnesium content. Komatiite was named for its type locality along the Komati River in South Africa, and frequently displays spinifex texture composed of large dendritic plates of olivine and pyroxene.

<span class="mw-page-title-main">Heazlewoodite</span>

Heazlewoodite, Ni3S2, is a rare sulfur-poor nickel sulfide mineral found in serpentinitized dunite. It occurs as disseminations and masses of opaque, metallic light bronze to brassy yellow grains which crystallize in the trigonal crystal system. It has a hardness of 4, a specific gravity of 5.82. Heazlewoodite was first described in 1896 from Heazlewood, Tasmania, Australia.

<span class="mw-page-title-main">Népouite</span> Nickel ore from the serpentine family (phyllosilicate)

Népouite is a rare nickel silicate mineral which has the apple green color typical of such compounds. It was named by the French mining engineer Edouard Glasser in 1907 after the place where it was first described, the Népoui Mine, Népoui, Poya Commune, North Province, New Caledonia. The ideal formula is Ni3(Si2O5)(OH)4, but most specimens contain some magnesium, and (Ni,Mg)3(Si2O5)(OH)4 is more realistic. There is a similar mineral called lizardite in which all of the nickel is replaced by magnesium, formula Mg3(Si2O5)(OH)4. These two minerals form a series; intermediate compositions are possible, with varying proportions of nickel to magnesium.

<span class="mw-page-title-main">Millerite</span> Nickel sulfide mineral

Millerite or nickel blende is a nickel sulfide mineral, NiS. It is brassy in colour and has an acicular habit, often forming radiating masses and furry aggregates. It can be distinguished from pentlandite by crystal habit, its duller colour, and general lack of association with pyrite or pyrrhotite.

<span class="mw-page-title-main">Subduction zone metamorphism</span> Changes of rock due to pressure and heat near a subduction zone

A subduction zone is a region of the Earth's crust where one tectonic plate moves under another tectonic plate; oceanic crust gets recycled back into the mantle and continental crust gets produced by the formation of arc magmas. Arc magmas account for more than 20% of terrestrially produced magmas and are produced by the dehydration of minerals within the subducting slab as it descends into the mantle and are accreted onto the base of the overriding continental plate. Subduction zones host a unique variety of rock types formed by the high-pressure, low-temperature conditions a subducting slab encounters during its descent. The metamorphic conditions the slab passes through in this process generates and alters water bearing (hydrous) mineral phases, releasing water into the mantle. This water lowers the melting point of mantle rock, initiating melting. Understanding the timing and conditions in which these dehydration reactions occur, is key to interpreting mantle melting, volcanic arc magmatism, and the formation of continental crust.

The Coal Creek Serpentinite(Coal Creek Serpentine) is a name for a Precambrian rock formation that outcrops on the southeastern side of the Llano Uplift in Gillespie and Blanco counties, Texas. The Coal Creek Serpentinite is tabular south-dipping body of serpentinite. Its outcrop is about 3.7 mi (6.0 km) long along an east–west axis and varies in width from 0.3 to 1.4 mi (0.48 to 2.25 km). Along the central part of the body, the southern contact of the serpentinite slopes about 60° to the south and gradually decreases in dip to about 40° further west. The southern and northern contacts are shear zones. The serpentinite underlies a very sparsely vegetated east–west trending ridge.

Antigorite Monoclinic mineral

Antigorite is a lamellated, monoclinic mineral in the phyllosilicate serpentine subgroup with the ideal chemical formula of (Mg,Fe2+)3Si2O5(OH)4. It is the high-pressure polymorph of serpentine and is commonly found in metamorphosed serpentinites. Antigorite, and its serpentine polymorphs, play an important role in subduction zone dynamics due to their relative weakness and high weight percent of water (up to 13 weight % H2O). It is named after its type locality, the Geisspfad serpentinite, Valle Antigorio in the border region of Italy/Switzerland and is commonly used as a gemstone in jewelry and carvings.

<span class="mw-page-title-main">Taiwan Black Jade</span> Type of serpentine jade

Taiwan Black Jade is a type of serpentine jade, primarily composed of minerals such as antigorite and magnetite. It exhibits colors ranging from dark green to black. It is found in the Fengtian area of Hualien County, Taiwan. It was discovered during the mining of Taiwan Jade in the 1960s and 1970s but was not at that time recognized as a new variety of mineral. In the 2010s researchers conducted studies and analysis that identified it as a new type of serpentine jade.

References

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  8. Earth and Life Processes Discovered from Subseafloor Environments: A Decade of Science Achieved by the Integrated Ocean Drilling Program (IODP). Elsevier. 2014-12-03. ISBN   978-0-444-62611-0.
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