Thulite

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Thulite
Thulite.jpg
Thulite from Leksvik, Norway.
General
Category Sorosilicate variety
Formula
(repeating unit)
(Ca,Mn)2Al3(SiO4)(Si2O7)O(OH)
Crystal system Orthorhombic
Identification
ColorPink
Crystal habit Massive
Cleavage Perfect {010} imperfect {100}
Fracture Uneven to conchoidal
Mohs scale hardness6.5
Luster Vitreous, pearly on cleavage surfaces
Streak White or colorless
Specific gravity 3.10-3.38
Optical propertiesbiaxial positive
Refractive index 1.69-1.70
Birefringence 0.006-0.018
Pleochroism Present, dichroism or trichroism depending on color.

Thulite (sometimes called rosaline) is a translucent, crystalline or massive pink manganese-bearing variety of the mineral zoisite. Manganese substitutes for calcium in the structure with up to two percent Mn2+. [1] Thulite is often mottled with white calcite and occurs as veins and fracture fillings transecting many types of rock. In mineralogical literature, thulite may sometimes refer to any pink zoisite. Clinothulite is the manganese bearing variety of monoclinic clinozoisite. [2]

Thulite was first discovered at a place called Sauland in Telemark, Norway in 1820. [3] It is named after the mythical island of Thule in the belief that the island is Scandinavia. [3] Thulite is used as a gemstone and carving material in the manufacture of jewelry and ornamental objects.

Thulite is also found in the Austrian Tyrol and in Mitchell County, North Carolina. A new, more recent find of a small quantity of thulite was discovered near Riverside in Okanogan County, Washington, US [3] and in Snillfjord i Trøndelag, Norway during tunnel constructions in December 2018. [4] Thulite is also found in New Zealand in the Otago region of the south island . It's a rare mineral and better quality then NZ rhodonite

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Beryl Gemstone: beryllium aluminium cyclosilicate

Beryl ( BERR-əl) is a mineral composed of beryllium aluminium cyclosilicate with the chemical formula Be3Al2Si6O18. Well-known varieties of beryl include emerald and aquamarine. Naturally occurring, hexagonal crystals of beryl can be up to several meters in size, but terminated crystals are relatively rare. Pure beryl is colorless, but it is frequently tinted by impurities; possible colors are green, blue, yellow, and red (the rarest). Beryl can also be black in color. It is an ore source of beryllium.

Tourmaline Cyclosilicate mineral group

Tourmaline is a crystalline boron silicate mineral compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is classified as a semi-precious stone. This gemstone can be found in a wide variety of colors.

Hornblende A complex inosilicate series of minerals

Hornblende is a complex inosilicate series of minerals. It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole.

Lepidolite

Lepidolite is a lilac-gray or rose-colored member of the mica group of minerals with formula K(Li,Al,Rb)2(Al,Si)4O10(F,OH)2. It is the most abundant lithium-bearing mineral and is a secondary source of this metal. It is a phyllosilicate mineral and a member of the polylithionite-trilithionite series. Lepidolite is part of a three-part series consisting of polylithionite, lepidolite, and trilithionite. All three minerals share similar properties and are caused because of varying ratios of lithium and aluminum in their chemical formulas. The Li:Al ratio varies from 2:1 in polylithionite up to 1.5:1.5 in trilithionite.

Zoisite

Zoisite, first known as saualpite, after its type locality, is a calcium aluminium hydroxy sorosilicate belonging to the epidote group of minerals. Its chemical formula is Ca2Al3(SiO4)(Si2O7)O(OH).

Anyolite

Although anyolite is advertised as a variety of the mineral zoisite from Kenya and the Arusha Region of Tanzania, anyolite is actually a metamorphic rock composed of intergrown green zoisite, black/dark green pargasite, and ruby. The term anyolite is however not an officially accepted term for a metamorphic rock. It is said to be named after the Maasai word anyoli, meaning "green." Anyolite is also referred to as ruby in zoisite, ruby zoisite, ruby-zoisite or Tanganyika artstone.

Staurolite

Staurolite is a reddish brown to black, mostly opaque, nesosilicate mineral with a white streak. It crystallizes in the monoclinic crystal system, has a Mohs hardness of 7 to 7.5 and the chemical formula: Fe2+2Al9O6(SiO4)4(O,OH)2. Magnesium, zinc and manganese substitute in the iron site and trivalent iron can substitute for aluminium.

Epidote Sorosilicate mineral

Epidote is a calcium aluminium iron sorosilicate mineral.

Pyrolusite

Pyrolusite is a mineral consisting essentially of manganese dioxide (MnO2) and is important as an ore of manganese. It is a black, amorphous appearing mineral, often with a granular, fibrous, or columnar structure, sometimes forming reniform crusts. It has a metallic luster, a black or bluish-black streak, and readily soils the fingers. The specific gravity is about 4.8. Its name is from the Greek for fire and to wash, in reference to its use as a way to remove tints from glass.

Tephroite

Tephroite is the manganese endmember of the olivine group of nesosilicate minerals with the formula Mn2SiO4. A solid solution series exists between tephroite and its analogues, the group endmembers fayalite and forsterite. Divalent iron or magnesium may readily replace manganese in the olivine crystal structure.

Adamite

Adamite is a zinc arsenate hydroxide mineral, Zn2AsO4OH. It is a mineral that typically occurs in the oxidized or weathered zone above zinc ore occurrences. Pure adamite is colorless, but usually it possess yellow color due to Fe compounds admixture. Tints of green also occur and are connected with copper substitutions in the mineral structure. Olivenite is a copper arsenate that is isostructural with adamite and there is considerable substitution between zinc and copper resulting in an intermediate called cuproadamite. Zincolivenite is a recently discovered mineral being an intermediate mineral with formula CuZn(AsO4)(OH). Manganese, cobalt, and nickel also substitute in the structure. An analogous zinc phosphate, tarbuttite, is known.

Vesuvianite

Vesuvianite, also known as idocrase, is a green, brown, yellow, or blue silicate mineral. Vesuvianite occurs as tetragonal crystals in skarn deposits and limestones that have been subjected to contact metamorphism. It was first discovered within included blocks or adjacent to lavas on Mount Vesuvius, hence its name. Attractive-looking crystals are sometimes cut as gemstones. Localities which have yielded fine crystallized specimens include Mount Vesuvius and the Ala Valley near Turin, Piedmont.

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.

Clinozoisite

Clinozoisite is a complex calcium aluminium sorosilicate mineral with formula: Ca2Al3(Si2O7)(SiO4)O(OH). It forms a continuous solid solution series with epidote by substitution of iron(III) in the aluminium (m3 site) and is also called aluminium epidote.

Seamanite

Seamanite, named for discoverer Arthur E. Seaman, is a rare manganese boron phosphate mineral with formula Mn3[B(OH)4](PO4)(OH)2. The yellow to pink mineral occurs as small, needle-shaped crystals. It was first discovered in 1917 from a mine in Iron County, Michigan, United States and identified in 1930. As of 2012, seamanite is known from four sites in Michigan and South Australia.

Sauland Village in Eastern Norway, Norway

Sauland is a village (parish) and the administrative center in Hjartdal municipality in Telemark county. The population is above 800 people in 2016, which equates over half of all households in the whole municipality. The village is placed in the south/east corner of the municipality and is one of the three parishes in Hjartdal. The place was until Notodden was founded, a center in Aust-Telemark, and had at this time the magistrate for the district. Until 1860 it had its own separate stave church, which was torn down and replaced with the wooden church that stands today.

Bustamite

Bustamite is a calcium manganese inosilicate (chain silicate) and a member of the wollastonite group. Magnesium, zinc and iron are common impurities substituting for manganese. Bustamite is the high-temperature polymorph of CaMnSi2O6 and johannsenite is the low temperature polymorph. The inversion takes place at 830 °C (1,530 °F), but may be very slow.
Bustamite could be confused with light-colored rhodonite or pyroxmangite, but both these minerals are biaxial (+) whereas bustamite is biaxial (-).

Serandite

Serandite is a mineral with formula Na(Mn2+,Ca)2Si3O8(OH). The mineral was discovered in Guinea in 1931 and named for J. M. Sérand. Serandite is generally red, brown, black or colorless. The correct name lacks an accent.

Caryopilite

Caryopilite (synonymous with ectropite and ektropite) is a brown-colored mineral with formula (Mn2+,Mg)3Si2O5(OH)4. The mineral was discovered in 1889 from a mine in Sweden. It was named for the Greek words for walnut and felt in reference to its appearance.

Hexagonite

Hexagonite is the red to pink, lilac to purple manganoan variety of tremolite. A rare amphibole, it can be transparent, translucent, and rarely opaque.

References

  1. Deer, Howie and Zussman, An Introduction to the Rock Forming Minerals, Longman, 1966, p. 62, ISBN   0-582-44210-9
  2. http://www.mindat.org/min-27132.html Mindat - Clinothulite
  3. 1 2 3 Mindat with location data
  4. https://www.nrk.no/trondelag/stort-funn-av-det-rosa-mineralet-thulitt-far-norske-hobbygeologer-til-a-juble-1.14324283