FRIEDELITE: Franklin, New Jersey (1.74)
Friedelite is not abundant, and little material has been faceted. The cabochons cut from Franklin material are lovely, rich colored, and usually translucent. The faceted gems are exceedingly rare and true collector items. Such stones are seldom seen even in large collections. Cabochons of material from the deep manganese mine at Kuruman, South Africa are rose-red and translucent.
Friedelite Value
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Friedelite Information
| Data | Value |
| Name | Friedelite |
| Crystallography | Hexagonal (R). Crystals are tabular, needlelike, hemimorphic, and very rare. Usually massive, fibrous aggregates, cryptocrystalline. |
| Colors | Pale pink to dark brownish red, red. brown, orange-red. |
| Luster | Vitreous |
| Hardness | 4-5 |
| Density | 3.04-3.07 |
| Birefringence | 0.030 |
| Cleavage | Perfect 1 direction. Fracture uneven. Brittle. |
| Stone Sizes | Translucent stones up to 1-5 carats normal; cabochons to about 30 x 40 mm. The larger stones lose any transparency. |
| Luminescence | May be reddish in LW and SW. Some material green (SW) and yellow /LW). |
| Spectral | Broad band at 5560 and also 4560 (indistinct); spectrum not diagnostic. |
| Formula | (Mn, Fe)8Si6O18(OH, CI)4· 3H20. |
Optics: o = 1.654-1.664; e = 1.625-1.629. Uniaxial (-).
Usually refractometer shows shadow edge at about 1.645.
Occurrence: In manganese deposits. Orebro, Sweden; Adervielle, France; USSR; Austria. Franklin, New Jersey: source of gem material. Usually brownish, cryptocrystalline and looks like a fibrous chalcedony. Seams of the material at this deposit were up to 2 inches wide. Kuruman, South Africa: massive dark rose red.
Comments: Friedelite is not abundant, and little material has been faceted. The cabochons cut from Franklin material are lovely, rich colored, and usually translucent. The faceted gems are exceedingly rare and true collector items. Such stones are seldom seen even in large collections. Cabochons of material from the deep manganese mine at Kuruman, South Africa are rose-red and translucent.
Name: After the French chemist and mineralogist, Charles Friedel.
