NORBERGITE MARBLE SPECIMEN

Norbergite Marble Specimen to add to your Fluorescent Mineral Collection.  This large specimen is from Stirling Hill and hard to come by.  Pics taken with Short Wave UV or UVC lamp and Long Wave UV or UVA torch.  We found this one in some old stock.  The Yellow is Norbergite, The Blue is Diopside and Pink is Calcite.

Location:
Stirling Hill Mine, Franklin, New Jersey, USA.

Dimensions:
6.9cm x 7.8cm x 8.7cm, 456g.

NORBERGITE
Magnesium Silicate Fluoride Hydroxide,
Mg3SiO4(F, OH)2.

Norbergite is one of several rare yet collectable minerals from the famous mines at Franklin, New Jersey.  It is one of the many minerals there that are fluorescent.  Norbergite will glow a tan to yellow colour when subjected to shortwave UV light.  Associated with Diopside and Calcite.  The combination of different fluorescing colours can be very attractive.  Norbergite was first discovered in Norberg, Sweden from where it gets it name.  It forms as small grains in the marbles of contact metamorphic environments.

Norbergite is a member of the Humite Group of minerals.  Noted for having a mixture of silicate and oxide layers in their structures.  The silicate layers have the same structure as Olivine.  The oxide layers have the same structure as Brucite.  Norbergite is the only member of the group with just one Olivine layer which alternates with the Brucite layer.  The formula could be written Mg2SiO4  Mg(F, OH)2.

This formula distinguishes the chemistry of the two layers.  The most common member of the Humite Group is Chondrodite which has two Olivine layers between each Brucite layer.  Humite, the namesake of the group, has three.

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