Erniggliite,
named in honor of Ernst Niggli, ordinary professor emeritus at the Institute
of Mineralogy Bern, and former president and founding member of the AGL, was
found in Lengenbach in March 1986 in the block described in the history section
(Graeser et al., 1992). Location of type specimen material is not stated but
is presumed to be the Natural History Museum in Basel.
The mineral that is trigonal, is characterized by containing
tin, a metal never before found in Lengenbach. Also, it is the first known mineral
containing thallium and tin. Crystals have a maximum of 0.5 mm and apparently
are hexagonal. The color is black to gray in the pinacoid and shiny black in
the remaining faces. The streak is reddish-black. It is found associated with
many minerals, including hutchinsonite, hatchite, wallisite, lorandite, bernardite,
edenharterite, stalderite, realgar and orpiment.
Interestingly, both the type
crystals of edenharterite and erniggliite are on the same specimen, that one
which carries the catalog number L18393.
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