36 Photos
Hubnerite
Chemical Formula	MnWO4
Species	Molybdates & Tungstates
Crystal System	Monoclinic
Mohs Scale	4-4.5
Specific Gravity	7.12-7.18
Color	Yellowish brown to reddish brown, blackish brown, black; Deep red internal reflections in reflected light
Streak	Yellow to reddish brown, greenish gray
Luster	Metallic to adamantine towards resinous.
Refractive Index	nα=2.17-2.2, nβ=2.22, nγ=2.3-2.32
Diaphaneity	Transparent to translucent
Cleavage	Perfect on
Fracture	Irregular/uneven
Crystal Habit：Prismatic striated crystals, tabular to flattened, in radiating groups

Hübnerite or hubnerite is a mineral consisting of manganese tungstate (chemical formula: MnWO₄). It is the manganese endmember of the manganese - iron wolframite solid solution series. It forms reddish brown to black monoclinic prismatic submetallic crystals. The crystals are typically flattened and occur with fine striations. It has a high specific gravity of 7.15 and a Mohs hardness of 4.5. It is transparent to translucent with perfect cleavage. Refractive index values are nα=2.170 - 2.200, nβ=2.220, and nγ=2.300 - 2.320.

Typical occurrence is in association with high-temperature hydrothermal vein deposits and altered granites with greisen, granite pegmatites and in alluvial deposits. It occurs associated with cassiterite, arsenopyrite, molybdenite, tourmaline, topaz, rhodochrosite and fluorite.

It was first described in 1865 for an occurrence in the Erie and Enterprise veins, Mammoth district, Nye County, Nevada, and named after the German mining engineer and metallurgist, Adolf Huebner from Freiberg, Saxony.

Abstract

Hübenerite is a rare mineral from a rare family the wolframite family to be more specific. It is the manganese rich mineral of the wolframite family. The structure of hübenerite consists of tetrahedral groups and octahedral groups. The wolframite family is a rare family that is usually found in pegmatites and high-temperature quartz veins associated with granites. Rarely the wolframite family can be seen in the sulfide veins.

Introduction

Hübenerite is a rare mineral from the rare family wolframite. It is considered to be one of the principle ore of tungsten. It is usually identified by the dark color, one direction of perfect cleavage and high specific gravity all serving to distinguish it from other minerals. The first recorded identification of the wolframite family was back in 1948 but it was not added as a mineral until 1951 (King, 2005).

Composition

Since the hübenerite comes from a family with only two end members it would be easier to explain the composition of the wolframite family since there is not enough data on the hübenerite itself. The primary formula of the wolframite series is (Fe,Mn)WO4. The domination of either iron or manganese would result in forming one of two minerals. The iron dominated one will result in forming ferberite while the manganese denominated one will result in forming hübenerite (Errandonea & Segura, 2010). Hübenerite is rarer than ferberite due to the difficulty of iron and manganese substitution. There is also a magnesium substitution involved to form an MgWO4 (Neiva, 2008). This magnesium rich usually referred to as wolframite but it is not a mineral it is a crystal scintillator.

Structure

Same for the structure since the hübenerite is a rare member of rare family wolframite the structure of the family will be the structure of the members. Distorted tetrahedral (WO4) and octahedral ((Fe. Mn)O6) is the usual structure of all member in the wolframite family. Complete soid solution occurs between Fe2+ and Mn 2+ in the members of the series (King, 2005). In ferberite presented percentage of WO3 is around 76.3% while in hübenerite the percentage is around 76.6%. In natural occurrence the percent range fall within 20-80 percent of the wolframite series. In the past it was thought the wolframite family possess orthorhombic symmetry but in fact it is possess monoclinic symmetry. Short prismatic, lattened or wedge-shaped are the common crystals of the wolframite itself. In some rare occasions the crystals occur doubly-terminated. It is common for the faces to striated parallel to the c axis (Neiva, 2008). In most cases wolframite is embedded in quartz as subparallel crystalline masses.

Physical Properties

The color difference in the members is clear and marked. The color of hübenerite has a variation from yellowish-brown to reddish-brown (Errandonea & Segura, 2010). Crystal and crystalline masses of hübenerite show a verity of lusters from adamantine, submetallic to resinous luster (Dutrow & klein, 2007). In thin splints hübenerite can be either transparent or translucent. The streak is related to the color being a shade lighter (King, 2005). All the wolframite family members possess a perfect cleavage on {010}. On {100} and {102} there is less-well developed parting. In hübenerite the fracture is brittle and uneven. Is common for all members of the wolframite to show simple contact twins on {100} or rarely interpenetrant twins on {001}. The hardness of hübenerite is between 4 and 4.5 and density between 7.12 and 7.18. Table 1. The physical properties of hübenerite Physical Property Descriptions Cleavage Perfect cleavage on {010} Fracture Uneven and brittle fracture Color Yellowish-brown to reddish-brown Streak Yellowish-brown to reddish-brown Luster Sub-metallic, adamantine or resinous Twinning Simple contact twins Hardness 4.0 – 4.5 Density 7.12 – 7.18

Geological occurrence

Hübenerite is a rare mineral from a rare family called wolframite. Hübenerite grows in various places all over the world like in North America hübenerite grows in different places in the US, in South America it grows in Peru, Bolivia and Argentina, in Europe it grows in Germany, France, and other places, in Asia it grow in Russia, China, Japan and Kazakhstan. It is true that hübenerite grows all over the world but the quantity of it is small. Hübenerite usually found in embedded in pegmatites and high-temperature quartz veins. Hübenerite does not grow by itself usually (Neiva, 2008) . Usually it is associated with other minerals like cassiterite, scheelite, quartz, galena, arsenopyrite, bismuth, pyrite, and sphalerite.

History and Uses

Hübenerite was not the original name giving to the mineral. Hübenerite is the synonym of the original name Megabslte. The name Megabbslte was given to mineral by A. Brelthaupt in 1852. The name hübenerite was given the mineral by E.N Rlotte back in 1865. The name was given to honor the metallurgist Hüttenmelster Adolph Hübner (King, 2005). Hübenerite was obtainable from different sources in United Kingdom, but all of these sources are gone and it is no longer available. This might explain why hübenerite is a rare mineral. In Europe it is still a possible to get hübenerite Portugal and Germany. Hübenerite is primary used as a source of tungsten. Tungsten used to hardening metal in the manufacture of high-speed tools (Dutrow & klein, 2007).