Polylithionite
KLi2AlSi4O10(F,OH)2
Monoclinic. Point Group: 2/m
Space Group: C2/  Z = 2

The lithium mica polylithionite is found in coarse platy masses many cm across. It is generally transparent under the microscope and pale yellow to greenish in aggregate.

Polylithionite. A large coarsely-crystallized 'book' fluorescing pale yellow and yellow-white under shortwave ultraviolet. Field width 7 cm.

Under shortwave ultraviolet, polylithionite fluoresces yellowish-white. The fluorescent intensity varies; when dim the fluorescence may have a greenish cast, when bright it is nearly white. Polylithionite is not noticeably fluorescent under midwave or longwave ultraviolet.

Note assertions by some mineral collectors (e.g. Robbins 1983, 1994) that polylithionite fluoresces a “lemon” yellow are grossly inaccurate for Ilímaussaq material: the color is nothing like any lemon.

Polylithionite. Detail of thin transparent plates. Daylight at left, shortwave ultraviolet at right. Field width 1.5 cm.

Polylithionite occurs in various secondary assemblages and can be found with a wide variety of other secondary minerals—some of which also fluoresce—providing for stunning specimens.

Polylithionite. Daylight at left, shortwave ultraviolet at right. Specimen height 9 cm.

 

 
 
 
 


This page edited: June 06, 2005.    SimpleThinking