allactite

allactite

[ə′lak‚tīt]
(mineralogy)
Mn7(AsO4)2(OH)8 A brownish-red mineral consisting of a basic manganese arsenate.
References in periodicals archive ?
1954 Synadelphite and Allactite, Nordmark, Sweden, no.
At the Norwegian locality, the mineral occurs in lenses (up to 200 m long) in serpentine-magnesite rocks; other minerals found in these lenses are: althausite, holtedahlite, heneuite and a new mineral with the formula [Mg.sub.7][([PO.sub.4]).sub.2][(OH).sub.8] isostructural with allactite, [Mn.sub.7][(As[O.sub.4]).sub.2][(OH).sub.8].
[Relationship to other species: It is the Mg- and [PO.sub.4]-dominant analogue of allactite, [Mn.sub.7][([AsO.sub.4]).sub.2][(OH).sub.8].
Hydrocerussite and rare allactite have also been noted in this assemblage.
The magnesium- and phosphate-dominant analogue of allactite
I worked my way through scores of exotic specimens which up till then were only names in mineralogy texts to me: perite, allactite, akrochordite, paulmooreite, molybdophyllite, and eveite (the manganese analog of adamite, whose naming once elicited much criticism for its flippancy).