Canavesite, Mg₂(HBO₃)(CO₃)∙5H₂O, is a rare carboborate mineral from the abandoned Brosso mine in Italy. Canavesite is a secondary mineral that occurs due to the weathering of ludwigite-magnetite skarn on the surface of mine walls. The physical properties consist of milky-white rosette-like aggregates of elongated transparent fibers shown in figure one.Chao, G.Y., Fliesher, Mandarino, J.A. (1979) New Mineral Names*.,American Mineralogist, 64, 652–659. It has the

crystal symmetry In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric patterns t ...

of a

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...

with a diffraction symbol of ''2/mP-/-''.

History

Giussani & Vighi saw and described boron mineralization in 1964 in a pyrite mine, Brosso, in

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...

. They noticed secondary minerals forming between szaibelyite and

ludwigite Ludwigite is a magnesium-iron borate mineral: Mg2FeBO5. Ludwigite typically occurs in magnesian iron skarn and other high temperature contact metamorphic deposits. It occurs in association with magnetite, forsterite, clinohumite and the borates ...

at the point where they come into contact with each other inside

magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. With th ...

skarns. Years later in 1972 a few members from the Gruppo Mineralogico Lombardo found the first sample of a new unknown mineral around the same location. Since then canavesite has been traded as

nesquehonite Magnesium carbonate, (archaic name magnesia alba), is an inorganic salt that is a colourless or white solid. Several hydrated and basic forms of magnesium carbonate also exist as minerals. Forms The most common magnesium carbonate forms are ...

and added to geologic collections. Canavestie is one of few known carboborates. The name canavesite originates from the district of Canavese where the

pyrite The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue giv ...

mine is located.Ferraris, G., Franchini-Angela, M.(1978) Canavesite, A New Carboborate Mineral from Brosso, Italy.,Canadian Mineralogist, 16, 69-73.

Composition

Canavesite has the chemical formula Mg₂(HBO₃)(CO₃)∙5H₂O, which makes it a carboborate mineral. Having two complete chemical analyses and one partial gives MgO (31.06),B₂O₃(12.70),CO₂(18.57)H₂O(37.44) and MgO (31.18),B₂O₃(13.47),CO₂(17.02)H₂O(38.33) in weight % oxides. Taking eleven

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...

ions, one can calculate from this data the empirical formula is: Mg_2.03(HBO₃)_1.09(CO₃)∙4.91H₂O.Anthony, J.W., Bideaux, R.,Bladh, K., and Nichols, M.(2003) Canavesite Mg₂(HBO₃)(CO₃)∙5H₂O. Handbook of Mineralogy,(Republished by the Mineralogist Society of America). A canavestie infrared spectrum is unlike that of well known families. It has bands near 3500, 1450, and 1000 cm-1 looks almost like OH⁻. With a dilute

HCl HCL may refer to: Science and medicine * Hairy cell leukemia, an uncommon and slowly progressing B cell leukemia * Harvard Cyclotron Laboratory, from 1961 to 2002, a proton accelerator used for research and development * Hollow-cathode lamp, a spe ...

at or near room temperature canavestie will produce tiny bubbles of gas and foam with hissing sounds. The molecular formula has not been obtained for canavesite. The approximate density was obtained using the heavy liquid method, which shows a density of 1.8 g cm⁻³.

Occurrence

The Vola Gera tunnel in the Brosso mine is located in a village northwest of Ivrea, Piedmont,

in Canavese district. The mine was initially a pyrite mine but it was abandoned. It is a well known mine for fine minerals that build up between the zone where

monzonite Monzonite is an igneous intrusive rock, formed by slow cooling of underground magma that has a moderate silica content and is enriched in alkali metal oxides. Monzonite is composed mostly of plagioclase and alkali feldspar. Syenodiorite is an o ...

stock and marbles interbedded in the mica schists of the Sesia-Lanzo zone. Mineralization of boron within

skarns were first reported by Giussani and Vighi in 1964. There has since been more canavesite discovered in

New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...

at the Sterling Mine. They are the only two places that have been known to produce the secondary mineral.

Physical properties

Canavesite occurs as a milky rosette-like aggregates of very thin 10elongated fibers on surfaces and along fractures of

and

skarns. Canavesite is an exceptionally rare secondary mineral that forms on the walls of the abandoned mine of Brosso,

and has formed since the mine was abandoned due to weathering of these

and

skarns. Canvesite has a

P 2/m crystal structure and does not fluoresce under an ultraviolent light. It also has thin and slightly flexible vitreous fibers that are elongated parallel to 10 Some crystal may show pseudohexagonal prismatic habit, but these cases are rare. The

X-ray powder diffraction An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30 ...

pattern strongest lines are 9.54(100)202, 8.12(40)(201), 7.80(18)(102,301), 4.56(21)(501,503), and 3.11(19)(407).

References

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External links

mindatHandbook of Mineralogywebmineral
Carbonate minerals Magnesium minerals Borate minerals Monoclinic minerals