Axinite-(Mn) from the Franklin Mine, New Jersey
Contributed by: Michael Crawford
Date: Jul 18th, 2025
Locality: Franklin Mine, Franklin, Sussex County, New Jersey, USA (See on Mindat)
Size: 8 x 10.5 cm
Description:
This is a specimen of axinite-(Mn) (Ca2Mn2+Al2BSi4O15(OH)) from the Franklin Mine, Sussex County, New Jersey. Franklin is the type locality for axinite-(Mn). This mineral was initially called manganaxinite. The International Mineral Association (IMA) changed its name to axinite-(Mg) in 2007. Axinite-(Mn) belongs to the axinite group. Axinite-(Mg) and axinite-(Fe) are other minerals belonging to the axinite group. Axinite-(Mn) and axinite-(Mg) can be fluorescent. The specimen also contains non-fluorescent brown andradite, black franklinite, dark pink rhodonite, black hendricksite and green, fluorescent willemite.
This axinite-(Mn) has red fluorescence under longwave and shortwave UV illumination. It is non-fluorescent under midwave UV light. It is unusual for a mineral to be the same fluorescent color under longwave and shortwave UV light and non-fluorescent under midwave UV light. Axinite-(Mn) red fluorescence looks like calcite fluorescence, however axinite-(Mn) does not exhibit BIP (brief intense phosphorescence) when a UV light is swept across the mineral. Also, axinite-(Mn) is non-effervescent to acid.
The longwave and shortwave emission spectra have broad peaks with a maximum at 619 nm. The peaks are activated by manganese. Manganese probably replaces calcium in the axinite-(Mn) structure.
Summary of luminescence responses:
Axinite-(Mn) (Mindat) (RRUFF)
- Fluorescence under Longwave (365nm LED) UV light: Red
- Fluorescence under Shortwave (255nm LED) UV light: Red