apjohnite

apjohnite

[′ap‚jä‚nīt]
(mineralogy)
MnAl2(SO4)4·22H2O A white, rose-green, or yellow mineral containing water and occurring in crusts, fibrous masses, or efflorescences.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The mineral apjohnite is one of a number of surprises created by the interaction of elements such as iron pyrites from rock spoil from coal mining, sea water, and clay rocks.
Associated minerals are: coskrenite-(Ce), zugshunstite-(Ce), melanterite, halotrichite, pickeringite, apjohnite, epsomite and other hydrated sulfates.
Associated minerals are: coskreaite-(Ce), levinsonite-(Y), melanterite, halotrichite, picketingite, apjohnite, epsomite and other hydrated sulfates.
Associated minerals are: epsomite, members of the "hair salt" family (the most abundant of which is apjohnite), gypsum, jarosite, tschermigite, diadochite and four other new species: levinsonite-(Y), zugshunstite-(Ce), the probable ammonium analogue of slavikite and an iron phosphate.
Alum Cave Bluff, a Dana locality for apjohnite, epsomite, melanterite and potash alum, has yielded good microcrystals of several rare sulfate minerals, including three new rare-earth sulfates, and is the first North American occurrence of slavikite.
Alum Cave Bluff in the Great Smoky Mountains must be considered a classic locality, inasmuch as Dana's System (Palache et al., 1951; Dana, 1892) lists four unusual minerals (potash alum, epsomite, melanterite and apjohnite) from "Alum Cave." The locality was studied during the 1800's (Brown, 1884); however, the authors have found no record of any studies during this century, and a revisit for a modern investigation is therefore long overdue.
In 1981 one of the authors (TDC) became intrigued by the Dana mention of apjohnite and hiked up to Alum Cave Bluff to investigate.
Under "apjohnite," or manganese alum, we read that:
A bulk chemical analysis of one sample of Anakeesta phyllite is given in Table 1; note the comparatively high manganese content, which accounts for the existence of spessartine garnets in the greenschist-facies rock and the presence of apjohnite among the secondary minerals.
Apjohnite (Mn,Mg)[Al.sub.2][([SO.sub.4]).sub.4]*22[H.sub.2]O
Apjohnite occurs commonly as clear needles and silky masses of typical hair-salt appearance; most specimens of hair salt were identified as magnesian apjohnite by semiquantitative analysis with SEM/XRF (most analyses higher in Mn than Mg, with little or no Fe).
The mineral shows good cleavage normal to plates, and is found associated with magnesian apjohnite and epsomite, and sometimes with slavikite, ammoniojarosite, tschermigite, levinsonite-(Y), or zugshunstite-(Ce).