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 , and bjarebyite, ideally . 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 . 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.

==Introduction== Penikisite, ideally , is a second occurrence of kulanite. Both kulanite and penikisite are members of the bjarebyite group. Minerals in the bjarebyite group have the general formula where X=Ba, Y=, and Z=. Penikisite was found in a Yukon phosphate deposit near Rapid Creek. The mineral, along with kulanite, occurs in an iron-formation. In these iron-formations, Mg-rich zones were discovered and named penikisite in honor of Gunar Penikis who discovered these phosphate occurrences with Alan Kulan.