Penikisite

Penikisite was discovered by Alan Kulan and Gunar Penikis near Rapid Creek, Yukon Territory. The mineral is a member of the bjarebyite group along with kulanite, ideally BaFe2+2Al2(PO4)3(OH)3, and bjarebyite, ideally BaMn2+2Al2(PO4)3(OH)3. It is among several new minerals that have been discovered in the Rapid Creek and Big Fish areas of Yukon Territory. Kulanite is similar in many ways to penikisite in appearance and properties. The chemical formula for penikisite is Ba(Mg,Fe,Ca)Al2(PO4)2(OH)3. It has a hardness of about 4 and a density of 3.79 g/cm3. Penikisite is unique among the bjarebyite group in being monoclinic and has a biaxial optical class. It comes in shades of blue and green and, when rubbed on a streak plate, is pale green to white in color. Although penikisite and kulanite both range from blue to green, penikisite zones are easily distinguishable from kulanite zones in kulanite-penikisite crystals because they are lighter than the darker kulanite in color. Penikisite is a phosphate and is different from kulanite in that it is a magnesium-rich phosphate whereas kulanite is an iron-rich phosphate.