Stillwellite-(Ce)

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Stillwellite-(Ce)
Stillwellite-(Ce)-33971.jpg
1.3 cm stillwellite-(Ce) crystal in matrix
General
CategorySilicate mineral
Formula
(repeating unit)
(Ce,La,Ca)BSiO5
IMA symbol Swl [1]
Strunz classification 9.AJ.25
Dana classification54.02.03.02
Crystal system Trigonal
Crystal class Pyramidal (3)
H-M symbol: (3)
Space group P31
Identification
ColorRed-brown to pale pink
Crystal habit Flat rhombohedral crystals, massive
Twinning Observed on {100}
Cleavage Imperfect
Fracture Conchoidal
Mohs scale hardness6.5
Luster Resinous
Streak White
Diaphaneity Transparent to translucent
Specific gravity 4.57–4.6
Optical propertiesUniaxial (+)
Refractive index nω = 1.765, nε = 1.780
Birefringence δ = 0.015
Other characteristics Radioactive.svg Radioactive
References [2] [3] [4]

Stillwellite-(Ce) is a rare-earth boro-silicate mineral with chemical formula (Ce,La,Ca)BSiO5.

Contents

Location

It occurs as a metasomatic replacement of metamorphosed limestones in the Mary Kathleen mine, Australia and in alkalic pegmatites associated with syenite in an alkaline massif in Tajikistan. [2] It occurs in association with allanite, garnet, uraninite in the Australian deposit; with calcite, monazite, bastnasite, thorite, uranothorite and thorianite in the Desmont mine, Wilberforce, Ontario, Canada; and with pyrochlore, tienshanite, sogdianite, thorite, caesium kupletskite, reedmergnerite, steacyite, pectolite and quartz in the Tajikistan deposit. [2] It has also been reported from Mont Saint-Hilaire, Quebec, Canada and from Mineville, Essex County, New York. Other occurrences include the Inagli massif, Yakutia, Russia, around Langesundsfjord, Norway, in the Ilimaussaq intrusive complex, southern Greenland and the Vico volcano, Lazio, Italy. [2]

Discovery

It was first described in 1955 for an occurrence at the type locality is the Mary Kathleen Mine, 55 km (34 mi) east of Mount Isa, Queensland, Australia. It was named for Austrian mineralogist Frank Leslie Stillwell (1888–1963). [3] [4]

Chemistry Breakdown

(1)(2)(1)(2)

SiO2

22.4022.06La2O327.9519.12
UO20.22Ce2O333.1530.82
ThO25.41Pr2O31.82
B2O312.23[13.46]Nd2O35.36
Al2O30.42Sm2O30.34
Y2O30.740.28Fe2O30.18

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As
4
)
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•8H
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, or nickel arsenate form a complete series with the general formula (Co,Ni)
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(AsO
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)
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Adamite

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Bournonite Sulfosalt mineral species

Bournonite is a sulfosalt mineral species, trithioantimoniate of lead and copper with the formula PbCuSbS3.

Gahnite

Gahnite, ZnAl2O4, is a rare mineral belonging to the spinel group. It forms octahedral crystals which may be green, blue, yellow, brown or grey. It often forms as an alteration product of sphalerite in altered massive sulphide deposits such as at Broken Hill, Australia. Other occurrences include Falun, Sweden where it is found in pegmatites and skarns, Charlemont, Massachusetts; Spruce Pine, North Carolina; White Picacho district, Arizona; Topsham, Maine; and Franklin, New Jersey in the United States.

Enargite

Enargite is a copper arsenic sulfosalt mineral with formula Cu3AsS4. It takes its name from the Greek word enarge, "distinct". Enargite is a steel gray, blackish gray, to violet black mineral with metallic luster. It forms slender orthorhombic prisms as well as massive aggregates. It has a hardness of 3 and a specific gravity of 4.45.

Cerite Silicate mineral group containing cerium

Cerite is a complex silicate mineral group containing cerium, formula (Ce,La,Ca)
9
(Mg,Fe3+
)(SiO
4
)
6
(SiO
3
OH)(OH)
3
. The cerium and lanthanum content varies with the Ce rich species and the La rich species. Analysis of a sample from the Mountain Pass carbonatite gave 35.05% Ce
2
O
3
and 30.04% La
2
O
3
.

Libethenite

Libethenite is a rare copper phosphate hydroxide mineral. It forms striking, dark green orthorhombic crystals. It was discovered in 1823 in Ľubietová, Slovakia and is named after the German name of that locality (Libethen). Libethenite has also been found in the Miguel Vacas Mine, Conceição, Vila Viçosa, Évora District, Portugal, and in Tier des Carrières, Cahai, Vielsaim, Stavelot Massif, Luxembourg Province, Belgium.

Franckeite

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Fraipontite

Fraipontite is a zinc aluminium silicate mineral with a formula of (Zn,Al)3(Si,Al)2O5(OH)4.

Mckelveyite-(Y)

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Corderoite Extremely rare mercury sulfide chloride mineral

Corderoite is an extremely rare mercury sulfide chloride mineral with formula Hg3S2Cl2. It crystallizes in the isometric crystal system. It is soft, 1.5 to 2 on the Mohs scale, and varies in color from light gray to black and rarely pink or yellow.

Agrellite

Agrellite (NaCa2Si4O10F) is a rare triclinic inosilicate mineral with four-periodic single chains of silica tetrahedra.

Rhomboclase is an acidic iron sulfate mineral with a formula reported as H5Fe3+O2(SO4)2·2(H2O) or HFe(SO4)2·4(H2O). It crystallizes in the orthorhombic system and typically occurs as tabular crystals with a rhombic outline. It occurs as transparent colorless, blue, green, yellow or grey crystals with a vitreous to pearly luster.

Ancylite Group of hydrous strontium carbonate minerals

Ancylite is a group of hydrous strontium carbonate minerals containing cerium, lanthanum and minor amounts of other rare-earth elements. The composition is Sr(Ce,La)(CO3)2(OH)·H2O with ancylite-Ce enriched in cerium and ancylite-La in lanthanum.

Kegelite

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Awaruite

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Dzhalindite is a rare indium hydroxide mineral discovered in Siberia. Its chemical formula is In(OH)3.

Brockite

Brockite is a rare earth phosphate mineral with formula: (Ca,Th,Ce)PO4·H2O. It crystallizes in the hexagonal system in the chiral space group 180 or its enantiomorph 181. It is typically granular to massive with only rare occurrence of stubby crystals. It is radioactive due to the thorium content.

Mawsonite is a brownish orange sulfosalt mineral, containing copper, iron, tin, and sulfur: Cu6Fe2SnS8.

References

  1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID   235729616.
  2. 1 2 3 4 http://rruff.geo.arizona.edu/doclib/hom/stillwellitece.pdf Handbook of Mineralogy
  3. 1 2 http://webmineral.com/data/Stillwellite-(Ce).shtml Webmineral data
  4. 1 2 http://www.mindat.org/min-3788.html Mindat.org