Franklinite
Franklinite is an ore of zinc and manganese, two important metals that are industrial. This is a collector that is common mineral because of its typical associations with fluorescent minerals such as Calcite and Willemite. Franklinite is rarely available as a treasure that is faceted it is opaque, black and extremely brittle.
Franklinite is mostly known from the kind locality of Franklin, nj-new jersey, United States Of America but in addition found in a few other locations around the globe such as Långban, Värmland, Sweden; Hranicná, Czech Republic; Nayzatas, Dzhumart, and in the Ushkatyn deposits, Atasui area, Kazakhstan; the marble that is pereval, near Slyudyanka, Sayan Mountains, south of Lake Baikal, Siberia, Russia.
| Category: | Spinel structural group | |
| Formula: | ZnFe2O4 | |
| Ferrous Zincate | ||
| Crystallography: | Isometric – Hexoctahedral | |
| Crystal Habit: | Typically as octahedral crystals, dodecahedral less common, cubic rare; commonly with rounded edges, to 22 cm; may be modified. Also exsolved within other minerals; coarse to fine granular, massive. | |
| Twinning: | Twinning on {111} as both twin and composition plane, the spinel law, common. | |
| Cleavage: | None observed; Parting on [111], fair |
| Fracture: | Irregular/Uneven, Conchoidal |
| Tenacity: | Very Brittle |
| Hardness (Mohs): | 5.5 – 6.0 |
| Density: | 5.07 – 5.22 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Other: | Strongly to Weakly Magnetic; the variation in composition ratio of Zn:Fe results in a variable degree of magnetism. |
| Color: | Black, Iron-Black, Brownish Black, Reddish Black, may be tarnished; in reflected light, White to Gray, with dark Red internal reflections. |
| Transparency: | Opaque, Translucent in fine fragments |
| Luster: | Metallic, Sub-Metallic |
| Refractive Index: | 2.36(2) Isotropic R: (400) 19.2, (420) 19.2, (440) 19.2, (460) 19.2, (480) 19.2, (500) 19.1, (520) 19.0, (540) 18.6, (560) 18.2, (580) 17.8, (600) 17.4, (620) 17.1, (640) 16.8, (660) 16.6, (680) 16.4, (700) 16.3 |
| Birefringence: | 0.000 Isotropic |
| Pleochroism: | None |
