Humite (mineral group)
The humite group[1] is a group of nesosilicates with the general formula An(SiO4)m(F,OH)2.
When A is predominantly magnesium we have the humite subgroup:
- norbergite, Mg3(SiO4)(F,OH)2
- chondrodite, (Mg,Fe,Ti)5(SiO4)2(F,OH,O)2
- humite, (Mg,Fe)7(SiO4)3(F,OH)2
- clinohumite, (Mg,Fe)9(SiO4)4(F,OH)2
The manganese-humite subgroup has members
- alleghanyite, (Mn2+)5(SiO4)2(OH,F)2
- manganhumite, (Mn,Mg)7(SiO4)3(OH)2
- sonolite, Mn9(SiO4)4(F,OH)2
and the leucophoenicite subgroup has members
- ribbeite, Mn5(SiO4)2(OH)2
- leucophoenicite, (Mn,Ca,Mg,Zn)(SiO4)3(OH)2
- jerrygibbsite (Mn,Zn)9(SiO4)4(OH)2
Chondrodite is the most common member of the humite group. It may contain Ti up to 9.6% TiO2. Chondrodite from Sterling Hill Mine and Franklin Mine contains zinc to 11.5% ZnO and Mn to 36% MnO, and grades to alleghanyite.
The humite minerals commonly alter to serpentine or Mg-rich chlorite and dissolve by weathering, leaving iron oxide residues.[2]