Name/Title
Arsenopyrite / FluoriteEntry/Object ID
2009.62.18Description
Chemical Composition: FeAsS, CaF2
Crystal System: Orthorhombic System
Description: Common Name: Arsenopyrite / Fluorite
Chemistry: FeAsS Iron Arsenide Sulfide, CaF2, Calcium Fluoride
Group: Sulfide / Halides
Location: Yaogueng Xian Mine, China
Description: Heavy, metallic crystals of arsenopyrite with has some purple crystals of fluorite, the matrix appears to be pegmatite material with muscovite flakes.
PHYSICAL CHARACTERISTICS OF ARSENOPYRITE:
Color is a brassy white to gray.
Luster is metallic.
Transparency: Crystals are opaque.
Crystal System is orthorhombic; 2/m 2/m 2/m
Crystal Habits include prismatic crystals with a diamond cross section terminated by either a steep dome (actually two of the four faces of a prism) or a less inclined dome, also short stubby crystals doubly terminated with domes. Twinning is common, often bending the crystal and sometimes forming crosses, x's or stars.
Cleavage is distinct in two directions forming prisms.
Fracture is uneven.
Hardness is 5.5 - 6.
Specific Gravity is approximately 6.1+ (heavier than average for metallic minerals)
Streak is dark gray to black
Other Characteristics: Striations on dome faces, bitter smell when powdered or broken.
Associated Minerals are gold, siderite, pyrite and other sulfides.
Best Field Indicators are crystal habit, cleavage, smell when struck, color and luster
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
Fracture: uneven
Hardness: 5 Apatite
Luster: Metallic
Occurrence: Arsenopyrite is found in high temperature hydrothermal veins, in pegmatites, and in areas of contact metamorphism or metasomatism.
Fluorite may occur as a vein deposit, especially with metallic minerals, where it often forms a part of the gangue (the worthless "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.
Rock Type: Sedimentary
Specific Gravity: 6.1
Streak: dark gray to black
Texture: Microcrystaline
Variety: Arsenopyrite crystallizes in the monoclinic crystal system and often shows prismatic crystal or columnar forms with striations and twinning common. Arsenopyrite may be referred to in older references as orthorhombic, but it has been shown to be monoclinic. In terms of its atomic structure, each Fe center is linked to three As atoms and three S atoms.
Fluorite is a mineral with a veritable bouquet of brilliant colors. Fluorite is well known and prized for its glassy luster and rich variety of colors. The range of common colors for fluorite starting from the hallmark color purple, then blue, green, yellow, colorless, brown, pink, black and reddish orange is amazing and is only rivaled in color range by quartz. Intermediate pastels between the previously mentioned colors are also possible.
Fluorite has other qualities besides its great color assortments that make it a popular mineral. It has several different crystal habits that always produce well formed, good, clean crystals. The cube is by far the most recognized habit of fluorite followed by the octahedron which is believed to form at higher temperatures than the cube. Although the cleavage of fluorite can produce an octahedral shape and these cleaved octahedrons are popular in rock shops the world over, the natural (e.g. uncleaved) octahedrons are harder to find.
A rarer habit variety is the twelve sided dodecahedron however it is never seen by itself and usually modifies the cubic crystals by replacing the edges of the cube with one flat face of a dodecahedron. The tetrahexahedron is a twenty four sided habit that is also seen modifying the cubic habit. But instead of one face replacing each cubic edge, two faces modify the cube's edges. Occasionally combinations of a cube, dodecahedron and tetrahexahedron are seen producing an overall cubic crystal with no less that three minor parallel faces replacing each cubic edge. A fifth form is the hexoctahedron which modifies the cube by placing six very minor faces at each corner of the cube. Twinning is also common in fluorite and symmetrical penetration twins, especially from Cumberland England are much sought after by collectors.Collection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationDimensions
Width
7 inDepth
2-1/2 inLength
3 inWeight
3.12 ozDimension Notes
Dimension taken at widest pointsLocation
Location
Display Case
FS-12Room
Frieda Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Curtis GardnerDate
May 25, 2023Notes
Added current locationLocation
Container
LeftDrawer
Top shelfShelf
CenterCabinet
Case #42Wall
South wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
Permanent