Knebelite is a manganese variety of the fayalite-

tephroite Tephroite is the manganese endmember of the olivine group of nesosilicate minerals with the formula Mn2 Si O4. A solid solution series exists between tephroite and its analogues, the group endmembers fayalite and forsterite. Divalent iron or m ...

series with formula . It forms dark green

orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with a r ...

crystals. It is reported from a variety of locations in

Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...

as well as South Africa, Russia, British Columbia, New Hampshire, and Rhode Island.Knebelite on Mindat
/ref>

References

Manganese(II) minerals Iron(II) minerals Nesosilicates {{Manganese minerals