Formula: Mn2+9(SiO4)4(OH)2
Nesosilicate (insular SiO4 groups), leucophoenicite subgroup, humite group, orthorhombic paramorph of monoclinic sonolite, manganese-bearing mineral
Crystal System: Orthorhombic
Specific gravity: 4.00 measured, 4.07 calculated
Hardness: 5½
Streak: Pale pink
Colour: Violet pink to pinkish violet
Common impurities: Fe,Zn,Mg,Ca,H2O

Metamorphic environments

Jerrygibbsite occurs in a metamorphosed zinc-manganese deposit (Webmin). Leucophoenicite and sonolite are common associates (Mindat).

At the Wessels mine, Kalahari manganese field, South Africa, jerrygibbsite is intimately intergrown with leucophoenicite and sonolite (Dana).

At the type locality, the Franklin Mine, Sussex county, New Jersey, USA, jerrygibbsite occurs in a metamorphosed manganese-bearing zinc silicate and zinc oxide ore deposit (Mindat). It occurs in contact with franklinite, willemite, zincite and sonolite. In one of the type specimens jerrygibbsite is associated with, but not seen to be in contact with, leucophoenicite. On another specimen jerrygibbsite occurs in contact with sonolite (AM 69.546-552). The assemblages are notable for the lack of any calcium-bearing species. Jerrygibbsite appears to be a phase which requires zinc for its stability (AM 70.379-387).

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