MACKINAWITE

    Class : Sulfides and sulfosalts
    Subclass : Sulfides
    Crystal system : Tetragonal
    Chemistry : (Fe,Ni)9S8
    Rarity : Uncommon

Mackinawite is a nickel and iron sulfide widely distributed but always in very small quantities. It is a hydrothermal mineral observed in many high temperature copper or nickel deposits, and which also crystallizes during the serpentinization of peridotites. It is also found in certain meteorites. Its name comes from its location of discovery : the Mackinaw mine (Washington, USA). Machinawite very rarely occurs in automorphic lamellar crystals and almost exclusively forms very fine exsolutions, resembling flames or lamellae, in other sulfides, mainly chalcopyrite. It is bronze in color.

Main photo : Mackinawite (luminous white) in exsolution in twinned chalcopyrite from Akjoujt, Mauritania © Paul Picot

Mackinawite in the World

Beautiful but rare automorphic crystals, up to 15 mm long, come from copper and nickel deposits in Canada (dunites and pyroxenites from Muskox Hill) and Finland (Outokumpu). Among its other deposits, mackinawite is present in the serpentinites of Traversella (Piedmont, Italy), in the chalcopyrite and sphalerite sulfide masses of Skouriotissa (Cyprus), and in the large nickel deposit of Talnakh, near Norilsk (Siberia). In more surprising contexts, it is found in the Palabora carbonatite (South Africa) and in the Kramer borate deposit, near Boron (California).

Mackinawite in France

In France, mackinawite is described in numerous deposits but never in collection samples. We can note Chessy (Rhône), the serpentines of the Brioude sector (Haute-Loire), in the Alps, etc...

Twinning

No twin known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 2.5
Density : 4.17
Fracture : Undetermined
Streak : Black

TP : Opaque
RI : -
Birefringence : -
Optical character : -
Pleochroism : None
Fluorescence : None

Solubility : -

Magnetism : NoneRadioactivity : None

ReCaptcha

This service is used to secure web forms of our website and required if you want to contact us. By accepting it you agree to Google's privacy policy: https://policies.google.com/privacy

Google Analytics

Google Analytics is a service used on our website that tracks, reports traffic and measures how users interact with our website content in order for us to improve it and provide better services.

Facebook

Our website allows you to like or share its content on Facebook social network. By activating and using it you agree to Facebook's privacy policy: https://www.facebook.com/policy/cookies/

YouTube

Integrated videos provided by YouTube are used on our website. By accepting to watch them you agree to Google's privacy policy: https://policies.google.com/privacy

Twitter

Integrated tweets and share services of Twitter are used on our website. By accepting and using these you agree to Twitter's privacy policy: https://help.twitter.com/en/rules-and-policies/twitter-cookies

PInterest

Our website allows you to share its content on PInterest social network. By activating and using it you agree to PInterest's privacy policy: https://policy.pinterest.com/en/privacy-policy/