Minerals.net

i i Ferberite is the iron rich end member of the Wolframite series . It is not always...  More

Ferberite is the iron-rich end member of the Wolframite series. It is not always individually distinguished and is sometimes just classified as Wolframite. The presence of iron in its structure is responsible for its black color and opacity in relation to Huebnerite. Ferberite is named after German mineralogist Dr. Moritz Rudolph Ferber (1805-1875).
  Hide

Fluorite is a very popular mineral, and it naturally occurs in all colors of the spec...  More

Fluorite is a very popular mineral, and it naturally occurs in all colors of the spectrum. It is one of the most varied colored minerals in the mineral kingdom, and the colors may be very intense and almost electric. Pure Fluorite is colorless; the color variations are caused by various impurities. Some colors are deeply colored, and are especially pretty in large well-formed crystals, which Fluorite often forms. Sometimes coloring is caused by hydrocarbons, which can be removed from a specimen by heating. Some dealers may apply oil treatment upon amateur Fluorite specimens to enhance luster.

Fluorite has interesting cleavage habits. The perfect cleavage parallel to the octahedral faces can sometimes be peeled off to smooth out a crystal into a perfect octahedron. Many crystals, especially larger ones, have their edges or sections chipped off because of the cleavage.

Fluorite is one of the more famous fluorescent minerals. Many specimens strongly fluoresce, in a great variation of color. In fact, the word "fluorescent" is derived from the mineral Fluorite. The name of the element fluorine is also derived from Fluorite, as Fluorite is by far the most common and well-known fluorine mineral.

For additional information, see the gemstones section on Fluorite.
  Hide

Franklinite is named after the locality of Franklin, New Jersey, where it is found. T...  More

Franklinite is named after the locality of Franklin, New Jersey, where it is found. To date, this mineral is found only at Franklin and neighboring Ogdensburg, New Jersey. There are no other localities for Franklinite, but at these two localities it is quite abundant. Large crystals of previous mining eras are no longer found, and are considered classics that are highly sought-after by collectors.

Franklinite is usually associated with brilliantly fluorescent Calcite and Willemite, and may also occur with orange Zincite, providing specimens of nice color contrasting. Franklinite is sometimes classified as a variety of the mineral Magnetite, but it is in fact a distinct mineral species.  Hide