Name/Title
Ferberite / Fluorite / QuartzEntry/Object ID
2009.62.62Description
Chemical Composition: SEE DESCRIPTION
Crystal System: Orthorhombic System
Description: Common Name: Ferberite / Fluorite / Quartz
Chemistry: FeWO4, Iron Tungstate / CaF2, Calcium Fluoride / SiO2 , Silicon dioxide
Group: Sulfates / Halides / Silcate
Location: Jangxi, China
Description: Black blades next to a grouping of clear quartz crystals, with a large area of light blue fluorite crystals on one side of the specimen.
PHYSICAL CHARACTERISTICS OF FERBERITE:
Color is Black.
Luster is submetallic.
Transparency crystals are opaque.
Crystal System is monoclinic; 2/m
Crystal Habits include the flat, heavily modified, tabular crystals. The crystals are elongated along the b axis and are generally flattened in the a axis direction. Also as columnar aggregates and lamellar masses.
Cleavage is perfect in one direction parallel to the a and c axes.
Fracture is uneven.
Hardness is 4 - 4.5.
Specific Gravity is approximately 7.6 (heavy even for metallic minerals)
Streak is black.
Associated Minerals are quartz, hematite, tourmalines, cassiterite, micas and pyrite.
Other Characteristics: crystals are often striated.
Best Field Indicators are crystal habit, color, density, luster and cleavage.
THE PHYSICAL CHARACTERISTICS OF FLUORITE:
Color is extremely variable and many times can be an intense purple, blue, green or yellow; also colorless, reddish orange, pink, white and brown. A single crystal can be multi-colored.
Luster is vitreous.
Transparency: Crystals are transparent to translucent.
Crystal System: Isometric; 4/m bar 3 2/m
Crystal Habits include the typical cube and to a lesser extent, the octahedron as well as combinations of these two and other rarer isometric habits. Always with equant crystals; less common are crusts and botryoidal forms. Twinning also produces penetration twins that look like two cubes grown together.
Cleavage is perfect in 4 directions forming octahedrons.
Fracture is irregular and brittle.
Hardness is 4
Specific Gravity is 3.1+ (average)
Streak is white.
Other Characteristics: Often fluorescent blue or more rarely green, white, red or violet and may be thermoluminescent, phosphorescent and triboluminescent.
Associated Minerals are many and include calcite, quartz, willemite, barite, witherite, apatite, chalcopyrite, galena, sphalerite, pyrite and other sulfides.
Best Field Indicators are crystal habit, color zoning, hardness (harder than calcite, but softer than quartz or apatite), fluorescence and especially the octahedral cleavage.
PHYSICAL CHARACTERISTICS OF QUARTZ:
Color is as variable as the spectrum, but clear quartz is by far the most common color followed by white or cloudy (milky quartz). Purple (Amethyst), pink (Rose Quartz), gray or brown to black (Smoky Quartz) are also common. Cryptocrystalline varieties can be multicolored.
Luster is glassy to vitreous as crystals, while cryptocrystalline forms are usually waxy to dull but can be vitreous.
Transparency: Crystals are transparent to translucent, cryptocrystalline forms can be translucent or opaque.
Crystal System is trigonal; 3 2.
Crystal Habits are again widely variable but the most common habit is hexagonal prisms terminated with a six sided pyramid (actually two rhombohedrons). Three of the six sides of the pyramid may dominate causing the pyramid to be or look three sided. Left and right handed crystals are possible and identifiable only if minor trigonal pyramidal faces are present. Druse forms (crystal lined rock with just the pyramids showing) are also common. Massive forms can be just about any type but common forms include botryoidal, globular, stalactitic, crusts of agate such as lining the interior of a geode and many many more.
Cleavage is very weak in three directions (rhombohedral).
Fracture is conchoidal.
Hardness is 7, less in cryptocrystalline forms.
Specific Gravity is 2.65 or less if cryptocrystalline. (average)
Streak is white.
Other Characteristics: Striations on prism faces run perpendicular to C axis, piezoelectric (see tourmaline) and index of refraction is 1.55.
Associated Minerals are numerous and varied but here are some of the more classic associations of quartz (although any list of associated minerals of quartz is only a partial list): amazonite a variety of microcline, tourmalines especially elbaite, wolframite, pyrite, rutile, zeolites, fluorite, calcite, gold, muscovite, topaz, beryl, hematite and spodumene.
Best Field Indicators are first the fact that it is very common (always assume transparent clear crystals may be quartz), crystal habit, hardness, striations, good conchoidal fracture and lack of good cleavage
Fracture: conchoidal
Hardness: 3 Calcite
Luster: Vitreous
Occurrence: Ferberite typically occurs in pegmatites, granitic greisens and high temperature hydrothermal deposits. It is a minor ore of tungsten.
Fluorite may occur as a vein deposit, especially with metallic minerals, where it often forms a part of the gangue (the surrounding "host-rock" in which valuable minerals occur) and may be associated with galena, sphalerite, barite, quartz, and calcite. It is a common mineral in deposits of hydrothermal origin and has been noted as a primary mineral in granites and other igneous rocks and as a common minor constituent of dolostone and limestone.
Quartz occurs in hydrothermal veins as gangue along with ore minerals. Large crystals of quartz are found in pegmatites. Well-formed crystals may reach several meters in length and weigh hundreds of kilograms.
Rock Type: Sedimentary
Specific Gravity: 2.2
Streak: white
Variety: Ferberite is the iron endmember of the manganese - iron wolframite solid solution series.
Fluorite is a widely occurring mineral which is found in large deposits in many areas.
Quartz is the second most abundant mineral in the Earth's continental crust, after feldspar.Collection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationDimensions
Width
5 inDepth
2-3/4 inLength
5 inWeight
21.58 ozDimension Notes
Dimension taken at widest pointsLocation
Category
PermanentMoved By
Wendy MondryDate
January 12, 2010Location
Container
CenterDrawer
4th shelfShelf
Center, CenterWall
South wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Wendy MondryDate
January 12, 2010Location
Shelf
middle left, middle leftWall
south wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Joshua EspongeDate
September 19, 2009Category
Permanent