Penikisite
A variety of Minerals
What is 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 BaFe2Al2(PO4)3(OH)3, and bjarebyite, ideally BaMn2Al2(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/cm. 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.
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Penikisite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Penikisite Localities Map
See where Penikisite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Key Characteristics
Characteristics of Penikisite
Penikisite ranges from blue to green with a vitreous luster and, when rubbed along a streak plate, can be pale green to white. Depending on the thickness of the sample, the mineral can be either transparent or translucent. Penikisite is monoclinic with space group P21/m. The cell dimensions of this mineral were calculated by Mandarino and Sturman (1977) by least-squares refinement of the X-ray powder diffraction data to be: a 8.999, b 12.069, c 4.921Å. The mineral is non-fluorescent under short- and long-waves. It has a harness of about 4 and a density of 3.79(2) g/cm. There are two fair to good cleavages on {010} and {100}. Penikisite is biaxial (+) with nα 1.684(2), nβ 1.688(2), nγ 1.705(2). The 2V(γ) calculation is 56° and the 2V measurement is 52.2° . The pleochroism for penikisite is X grass-green, Y blue-green, Z pale pink. The absorption is X~Y>Z.
Composition of Penikisite
The chemical formula of Penikisite is Ba(Mg,Fe,Ca)Al2(PO4)2(OH)3. Mandarino and Sturman analyzed two penikisite samples and eight kulanite samples using an AMX electron miscroprobe (1977). Their study showed weight percent oxides, including H2O, that help determine what the formula is for penikisite and kulanite. Members of the bjarebyite group have the general formula XY2Z2(PO4)3(OH)3 where X=Ba, Y=Mg, Fe, Mn, and Z=Al, Fe. Accompanying penikisite in this group are as follows: bjarebyite, ideally BaMn2Al2(PO4)3(OH)3, perloffite, ideally BaMn2Fe2(PO4)3(OH)3, kulanite, BaFe2Al2(PO4)3(OH)3, and johntomaite, ideally BaFe2Fe2(PO4)3(OH)3. These minerals are identified when Ba in the X position is one of the most abundant elements in their composition along with being phosphates.
Quick Facts
Physical Properties
- Color
- Blue
- Hardness (Mohs)
- 4
- Streak
- White
Chemical Properties
- Chemical Formula
- Ba(Mg,Fe2+,Ca)2Al2(PO4)3(OH)3
- Elements
- Al, Ba, H, Mg, O, P
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Penikisite FAQs
How do I identify Penikisite?
Penikisite can be identified by its hardness of 4 on the Mohs scale, Blue color. Look for these key characteristics when examining specimens.
What color is Penikisite?
Penikisite typically appears in Blue. Color can vary depending on impurities and formation conditions.
How hard is Penikisite?
Penikisite has a hardness of 4 on the Mohs scale. This gives it moderate hardness.
What is the characteristics of penikisite of Penikisite?
Penikisite ranges from blue to green with a vitreous luster and, when rubbed along a streak plate, can be pale green to white. Depending on the thickness of the sample, the mineral can be either transparent or translucent. Penikisite is monoclinic with space group P21/m. The cell dimensions of this mineral were calculated by Mandarino and Sturman (1977) by least-squares refinement of the X-ray powder diffraction data to be: a 8.999, b 12.069, c 4.921Å. The mineral is non-fluorescent under short- and long-waves. It has a harness of about 4 and a density of 3.79(2) g/cm. There are two fair to good cleavages on {010} and {100}. Penikisite is biaxial (+) with nα 1.684(2), nβ 1.688(2), nγ 1.705(2). The 2V(γ) calculation is 56° and the 2V measurement is 52.2° . The pleochroism for penikisite is X grass-green, Y blue-green, Z pale pink. The absorption is X~Y>Z.
What is the composition of penikisite of Penikisite?
The chemical formula of Penikisite is Ba(Mg,Fe,Ca)Al2(PO4)2(OH)3. Mandarino and Sturman analyzed two penikisite samples and eight kulanite samples using an AMX electron miscroprobe (1977). Their study showed weight percent oxides, including H2O, that help determine what the formula is for penikisite and kulanite. Members of the bjarebyite group have the general formula XY2Z2(PO4)3(OH)3 where X=Ba, Y=Mg, Fe, Mn, and Z=Al, Fe. Accompanying penikisite in this group are as follows: bjarebyite, ideally BaMn2Al2(PO4)3(OH)3, perloffite, ideally BaMn2Fe2(PO4)3(OH)3, kulanite, BaFe2Al2(PO4)3(OH)3, and johntomaite, ideally BaFe2Fe2(PO4)3(OH)3. These minerals are identified when Ba in the X position is one of the most abundant elements in their composition along with being phosphates.
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