Serandite is a mineral with formula Na(Mn²⁺,Ca)₂Si₃O₈(OH). The mineral was discovered in

Guinea Guinea ( ),, fuf, 𞤘𞤭𞤲𞤫, italic=no, Gine, wo, Gine, nqo, ߖߌ߬ߣߍ߫, bm, Gine officially the Republic of Guinea (french: République de Guinée), is a coastal country in West Africa. It borders the Atlantic Ocean to the we ...

in 1931 and named for J. M. Sérand. Serandite is generally red, brown, black or colorless. The correct name lacks an accent.

Description

Serandite is transparent to translucent and is normally salmon-pink, light pink, rose-red, orange, brown, black, or colorless; in thin section, it is colorless. Octahedrally bonded Mn(II) is the primary contributor to the mineral's pink colors.Manning, p. 357. Crystals of the mineral can be prismatic to acicular and elongated along 10 bladed, blocky, or tabular and flattened on , occur as a radiating aggregate, or have massive habit. Sérandite is a member of the wollastonite group and is the manganese analogue of pectolite. It is sometimes used as a gemstone.Gemstones of North America - Volume 3 - Page 417 John Sinkankas - 1959

History

Serandite was discovered on Rouma Island, part of the

Los Islands LOS, or Los, or LoS may refer to: Science and technology * Length of stay, the duration of a single episode of hospitalisation * Level of service, a measure used by traffic engineers * Level of significance In statistical hypothesis testing, ...

in Guinea. The mineral was described by À. Lacroix in the journal '' Comptes rendus hebdomadaires des séances de l'Académie des Sciences''.Lacroix, p. 189. He named it ''sérandite'' in honor of J.M. Sérand, a mineral collector who helped in the collection of the mineral.

Occurrence and distribution

Serandite has been found in Australia, Brazil, Canada, Guinea, Italy, Japan, Namibia, Norway, Russia, South Africa, and the United States. The type material is held at the National Museum of Natural History in Washington, D.C. At Mont Saint-Hilaire, Quebec, serandite occurs in sodalite xenoliths and

pegmatite A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic com ...

s cutting

syenite Syenite is a coarse-grained intrusive igneous rock with a general composition similar to that of granite, but deficient in quartz, which, if present at all, occurs in relatively small concentrations (< 5%). Some syenites contain larger proport ...

s within an intrusive

alkalic Alkalinity (from ar, القلوي, al-qaly, lit=ashes of the saltwort) is the capacity of water to resist acidification. It should not be confused with basicity, which is an absolute measurement on the pH scale. Alkalinity is the strengt ...

gabbro 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 ...

complex. In Point of Rocks, New Mexico, it occurs in vugs in

phonolite Phonolite is an uncommon extrusive rock, of intermediate chemical composition between felsic and mafic, with texture ranging from aphanitic (fine-grained) to porphyritic (mixed fine- and coarse-grained). Phonolite is a variation of the igneou ...

. At the Tumannoe deposit in Russia, serandite occurs in a manganese rich deposit associated with

volcanic rock Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcan ...

s and

terrigenous In oceanography, terrigenous sediments are those derived from the erosion of rocks on land; that is, they are derived from ''terrestrial'' (as opposed to marine) environments. Consisting of sand, mud, and silt carried to sea by rivers, their c ...

(non-marine)

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sa ...

s which has been altered by

contact metamorphism Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chem ...

. Serandite has been found in association with

aegirine Aegirine is a member of the clinopyroxene group of inosilicate minerals. Aegirine is the sodium endmember of the aegirine-augite series. Aegirine has the chemical formula Na Fe Si2 O6 in which the iron is present as Fe3+. In the aegirine-augite ...

analcime Analcime (; ) or analcite is a white, gray, or colorless tectosilicate mineral. Analcime consists of hydrated sodium aluminium silicate in cubic crystalline form. Its chemical formula is Na Al Si2 O6· H2O. Minor amounts of potassium and calc ...

arfvedsonite Arfvedsonite () is a sodium amphibole mineral with composition: aNa2] Fe2+)4Fe3+(OH)2, Si8O22]. It crystallizes in the monoclinic prismatic crystal system and typically occurs as greenish black to bluish grey fibrous to radiating or stellate pr ...

astrophyllite Astrophyllite is a very rare, brown to golden-yellow hydrous potassium iron titanium silicate mineral. Belonging to the astrophyllite group, astrophyllite may be classed either as an inosilicate, phyllosilicate, or an intermediate between the two ...

, eudialyte,

fluorite Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs sca ...

leucophanite Leucophanite is an inosilicate mineral with the chemical formula . It may contain cerium substituting in the calcium position. It occurs in pegmatites and alkali igneous complexes as yellow, greenish or white triclinic crystals and has been fou ...

, mangan-neptunite,

microcline Microcline (KAlSi3O8) is an important igneous rock-forming tectosilicate mineral. It is a potassium-rich alkali feldspar. Microcline typically contains minor amounts of sodium. It is common in granite and pegmatites. Microcline forms during slow ...

nepheline Nepheline, also called nephelite (), is a rock-forming mineral in the feldspathoid groupa silica-undersaturated aluminosilicate, Na3 K Al4 Si4 O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatit ...

sodalite Sodalite ( ) is a tectosilicate mineral with the formula , with royal blue varieties widely used as an ornamental gemstone. Although massive sodalite samples are opaque, crystals are usually transparent to translucent. Sodalite is a member of th ...

, and

villiaumite Villiaumite is a rare halide mineral composed of sodium fluoride, Na F. It is very soluble in water and some specimens fluoresce under long and short wave ultraviolet light. It has a Mohs hardness of 2.5 and is usually red, pink, or orange in co ...

References

Bibliography

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External links