cummingtonite : List Of Minerals : The Stone Network
The Business To Business Portal For The Natural Stone Trade

Premium Black Galaxy Granite Slabs
Direct From The Factory
Ex-India

Mobile

Directory

Stone Fairs

Exhibitions 2017 Country
Exhibitions 2017 By Date

Stone Images

Granite
Limestone
Marble
Onyx
Quartzite
Sandstone
Slate
Travertine

Stone Machines

New Stone Machines
Used Stone Machines

Stone Sites

Stone Forums
Stone Magazines
Stone Portals

Stone Standards

CE Marking

Stone Supplies & Fabricators

Australia
Canada
United Kingdom
U.S.A.

Stone Testing

ASTM
BRE
Sandberg
Stats
Stone Initiatives
UKAS

Petrology

Granite
Limestone
Marble
Quartzite
Sandstone
Slate
Travertine

Rocks

Igneous
List of Minerals
List of Rocks
Metamorphic
Minerals
Sedimentary

Various Resources

A To Z Stone Names
Anti Slip
BIDA
Building Conservation
Building Design
English Heritage
Maintenance Products
Natural Stone Database
RIBA
RICS
Salvo
SPAB
Stone Federation GB
Trade Terminology

Cummingtonite or magnesium iron silicate hydroxide is a metamorphic amphibole with the chemical composition (Mg,Fe)7Si8O22(OH)2.

Monoclinic cummingtonite is compositionally similar and polymorphic with orthorhombic anthophyllite, which is a much more common form of magnesium-rich amphibole, the latter being metastable.

Cummingtonite shares few compositional similarities with alkali amphiboles such as arfvedsonite, glaucophane-riebeckite. There is little solubility between these minerals due to different crystal habit and inability of substitution between alkali elements and ferro-magnesian elements within the amphibole structure.

  • Chemistry
  • Cummingtonite is a member of the cummingtonite-grunerite solid solution series which ranges from Fe2Mg5Si8O22(OH)2 for cummingtonite to the iron rich grunerite endmember Fe7Si8O22(OH)2. Cummingtonite is used to describe minerals of this formula with between 30 and 70 per cent Fe7Si8O22(OH)2.

    Manganese also substitutes for (Fe,Mg) within cummingtonite amphibole, replacing B site atoms. These minerals are found in high-grade metamorphic banded iron formation and form a compositional series between Mn2Mg5Si8O22(OH)2 (tirodite) and Mn2Fe5Si8O22(OH)2 (dannemorite).

    Calcium, sodium and potassium concentrations in cummingtonite are low. Cummingtonite tends toward more Ca substitution than related anthophyllite. Similarly, cummingtonite has lower Fe3+ and Al than anthophyllite.

    Amosite is a rare asbestiform variety of grunerite that is mined as asbestos only in the eastern part of the Transvaal Province of South Africa. The origin of the name is Amosa, the acronym for the mining company "Asbestos Mines of South Africa."

    Cummingtonite was first described in 1824 for an occurrence near Cummington, Massachusetts, hence the name. It is also found in Sweden, South Africa, and Scotland.

  • Occurrence
  • Cummingtonite is commonly found in metamorphosed magnesium-rich rocks and occurs in amphibolites. Usually it coexists with hornblende or actinolite hornblende, magnesium clinochlore chlorite, talc, serpentine-antigorite minerals or metamorphic pyroxene. Magnesium-rich cummingtonite can also coexist with anthophyllite.

    Cummingtonite has also been found in some felsic igneous rocks such as dacites. Manganese rich species can be found in metamorphosed Mn-rich rock units. The Grunerite end member is characteristic of the metamorphosed iron formations of the Lake Superior region and the Labrador Trough. With prograde metamorphism cummingtonite and grunerite morph to members of the olivine and pyroxene series.

    Trade Supplies
    Information
    Information
  • Absolute Black Granite : Black Galaxy, Star Galaxy, Nero Impala etc. Black is popular, black looks great, black is more expensive >>>
  • Black Galaxy Granite : Quarrying & Quality Information >>>
  • M.I.A. Information
    Copyright :
    Legal Information
    This web site is protected under International Law by the
    Digital Millennium Copyright Act 1998.

    If you wish to link to this site please feel free to do so HOWEVER blatant design copying, code copying and theft of bandwidth will result in legal action!

    Digg Logo ImageDigg Facebook Logo ImageFacebook Reddit Logo ImageReddit StumbleUpon Logo ImageStumbleUpon Twitter Logo ImageTwitter

    Home : Contact : About : Legal : Privacy : Cookies : Copyright 1998-2017 : The Stone Network