Mimetite - Encyclopedia

    Class : Phosphates, arsenates, vanadates
    Subclass : Anhydrous arsenates
    Crystal system : Hexagonal
    Chemistry : Pb₅(AsO₄)₃Cl
    Rarity : Quite common

Mimetite belongs to the apatite group and is the arsenic pole of the mimetite-pyromorphite-vanadinite series. Very similar in appearance to the pyromorphite, it is from this characteristic that it owes its name : from the Greek mimetês (imitator). It is much rarer than the latter. Like pyromorphite, mimetite occurs in the oxidation zones of lead deposits. When pure, mimetite is colorless to yellowish with almost adamantine luster. It is a very rare case, the crystals are much more commonly yellow, yellow-orange to orange-red with resinous brightness, sometimes green. The crystals are prismatic surmounted by a pyramid, in hexagonal barrels with curved edges (campylite facies) or in reniform to globular masses. It can be in fibrous form, so it is called prixite. It is an ancillary ore of lead, these crystals are sought after by mineral collectors.

In France, mimetite is present in Molérats (Saône-et-Loire) where it is found in a fibrous form called prixite (second photo from the right), Lantignié (Rhône) where it is found associated with wulfenite, barite and fluorite (first photo on the right). It is also reported in millimetric transparent crystals in the old mine of Cap Garonne (Var). According to recent analyzes, however, it seems that the large yellow crystals with campylite facies of the Farges Mine in Corrèze are actually only pyromorphites.

There is a very rare twin on {11-22}.

No fake for this mineral species, but can sometimes be easily confused with pyromorphite, indeed without chemical analysis, it is sometimes impossible to tell the difference.