Vesuvianite

sorosilicate

grossular

Formula: (Ca,Na)19(Al,Mg,Fe)13(SiO4)10(Si2O7)4(OH,F,O)10
Sorosilicate (Si2O7 groups)
Specific gravity: 3.32 to 3.43
Hardness: 6½
Streak: White
Colour: Brown, yellow, brown-black, light green, emerald green, white, red, purple, violet, blue-green to blue
Solubility: Slightly soluble in hydrochloric acid
Environments:

Plutonic igneous environments
Pegmatites (USGS bulletin 445 Pegmatites of Maine)
Carbonatites
Metamorphic environments (typical)

Vesuvianite is usually formed as the result of contact and regional metamorphism of impure limestone. In contact metamorphism it is associated with other contact metamorphic minerals, such as grossular, andradite, wollastonite and diopside. It is also found in garnet-bearing gabbro, in nepheline syenite and in veins associated with mafic rocks and serpentinite.
Vesuvianite may be found in nepheline syenite, gabbro, limestone, skarn and serpentinite.

In metamorphic rocks vesuvianite is stable from temperatures below 300oC to above 900oC, depending on pressure.
In low-grade metamorphic environments with temperature below 300oC, major associated minerals are xonotlite, wollastonite, natrolite, thomsonite, pectolite and calcite, and other minerals that might be present include kirschsteinite, glaucochroite, aegirine, åkermanite, tobermorite, hydromagnesite and vuagnatite.
In medium grade metamorphic environments with temperature from about 300oC to 500oC, major associated minerals are grossular, diopside, magnesium-rich chlorite, prehnite, epidote and calcite, and other minerals that might be present include albite, titanite, apatite, dolomite, perovskite and zircon.
In high grade metamorphic environments, with temperatures above 500oC, major associated minerals are grossular, diopside, wollastonite, calcite, monticellite, melilite and quartz, and other minerals that might be present include spinel, epidote, plagioclase and zoisite (Lauf p146).

Occasional pseudomorphs of vesuvianite after melilite and after mica, presumably phlogopite, have been found (Lauf p168).

At the Kachuik pluton, Seward peninsula, Alaska, a metamict uranium and thorium bearing vesuvianite has been found in a radioactive syenite deposit with allanite, K-feldspar, hornblende and clinopyroxene (Lauf p146,165).

At the Pinchon marble quarry, near Malone, Ontario, Canada, vivianite crystals to 10 cm occur in the Grenville Province skarn (Lauf p148).

In the St Jovite area, Laurentides, Quebec, Canada, vesuvianite occurs in a regional metamorphic environment in calcite marble in a lens consisting of calcite, microcline, vesuvianite, quartz, diopside, calcium-rich plagioclase and wollastonite (Lauf p150).

At Mont Saint-Hilaire, Montérégie, Quebec, Canada, vesuvianite is found in xenoliths within the nepheline syenite, but more commonly in the contact zone between marble and syenite (Lauf p146).

At the Jeffrey quarry, Asbestos, Quebec, Canada, vesuvianite is found in hydrothermal veins in serpentinite, formed at 300 to 400oC and a pressure of 0 to 2 kbar (Lauf p150).

At Lough Anure, County Donegal, Ireland, vesuvianite occurs in skarn associated with wollastonite, grossular, diopside and tremolite (Lauf p148).

At the type locality, Monte Somma, Somma-Vesuvius Complex, Naples, Campania, Italy, vesuvianite is found in limestone blocks that have been ejected from the volcano and undergone intense thermal metamorphism, at 600 to 1050oC and a pressure of 0 to 2 kbar (Lauf p146).

Near the Arusha to Nairobi highway, between Kajiado and Namanga, Kenya, vesuvianite is found in a skarn deposit in crystalline limestone (Lauf p162).

At the Bau mining district, Sarawak, Malaysia, an antimony-rich vesuvianite has been reported, in a skarn-like rock where the ore is rich in stibnite and contains abundant wollastonite, epidote, quartz and calcite (Lauf p148).

At Lake Jaco, Coahuila, Mexico, vesuvianite occurs in skarn in an assemblage including calcite, quartz, grossular, vesuvianite, wollastonite and scapolite (Lauf p161).

In the Zhob valley, Baluchistan, Pakistan, vesuvianite has been found in serpentinite (Lauf p162).

In‌ the Swiss and Italian Alps vesuvianite is found in serpentinite of various metamorphic grades from 200 to 800oC and pressure from 0 to 6.5 kbar (Lauf p150).

In Tuva, Russia, metamict vesuvianite occurs in alkaline pegmatite associated with nepheline, microcline, thomsonite, other zeolites, cancrinite and albite (Lauf p146,165).

In the Wilui River region, Yakutia, Russia, a chlorine-rich vesuvianite occurs in rodingite-like metamorphic rocks associated with clinochlore, diopside, calcite, serpentine and garnets of the grossular - andradite series (Lauf p168).

At Långban, Sweden, bismuth-rich vesuvianite occurs in skarn associated with barium-rich K-feldspar, albite-rich plagioclase, lead-rich scapolite and phlogopite, with minor lead-rich epidote, vesuvianite and calcium-rich garnet (Lauf p168).

At the Crestmore quarry, Riverside county, California, vesuvianite occurs in skarn (Lauf p157).

At outcrops near the Dallas benitoite mine, San Benito county, California, USA, cerium-rich vesuvianite has been found associated with andradite variety melanite, perovskite and clinochlore (Lauf p164).

At the Bill Waley Allotment tungsten mine, Tulare county, California, USA, vesuvianite occurs in a deposit formed at the contact between granodiorite and marble by metasomatic replacement. Other minerals in the assemblage include löllingite, calcite, epidote, wollastonite, pyrrhotite and chalcopyrite (Lauf p157).

At Sanford, Maine, USA, crystals of vesuvianite to 17 cm are associated with quartz and occasionally with calcite, in a calc-silicate rock (Lauf p157).

At Manchester, New Hampshire, USA, vesuvianite is associated with garnet and scapolite in altered calcareous bands interbedded with lenses of granite and pegmatites (Lauf p148).

At Franklin, New Jersey, USA, beryllium-rich vesuvianite has been found as crystals embedded in a mixture of willemite, garnet, leucophoenicite, baryte and other species (Lauf p167).

Alteration

grossular, diopside, monticellite, calcite and H2O to vesuvianite, quartz and CO2
10Ca3Al2(SiO4)3 + 3CaMgSi2O6 + 3CaMg(SiO4) + 2CaCO3 + 8H2O ⇌ 2Ca19Al10Mg3(SiO4)10 (Si2O2)4O2(OH)8 + 3SiO2 + 2CO2
A common association in calc-silicate metamorphism can be represented by the above equation. Vesuvianite stability will tend to increase with increasing water and decrease as the activity of CO2 rises.

Common impurities: Fe,Be,B,F,Cu,Li,Na,K,Mn,Ti,Cr,Zn,H2O

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