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== Crystallography ==
== Crystallography ==
There are four formula units (Z = 4) per [[Crystal structure|unit cell]], and it has sides of lengths a = 13.44 Å, b = 11.73 Å and c = 16.93 Å, with the angle between {{overline|'''a'''}} and {{overline|'''c'''}} being β = 94.7°. <ref name=Dana/><ref name=Mindat/><ref name=HOM/>
Unit Cell Parameters: Z = 4
a = 13.44 Å, b = 11.73 Å, c = 16.93 Å β = 94.7° <ref name=Dana/><ref name=Mindat/><ref name=HOM/>
<b/>
<b/>
Crystals are short prismatic parallel to [201], up to 3 mm long, or pyramidal. They are striated on {100} parallel to [0{{overline|1}}0] and on {{{overline|1}}12} parallel to [110]. Forms which have been observed include (001), (100), ({{overline|1}}01), (112), (111), ({{overline|2}}23), ({{overline|1}}11) and ({{overline|2}}21).<ref name=AM15/> Curved crystals are common.<ref name=Mindat/><ref name=HOM/> The numbers in brackets are [[Miller indices]].
Crystals are short [[Prism (geometry)|prismatic]] parallel to [201], up to 3 mm long, or [[Pyramid (geometry)|pyramidal]]. They are striated on {100} parallel to [0{{overline|1}}0] and on {{{overline|1}}12} parallel to [110]. Forms which have been observed include (001), (100), ({{overline|1}}01), (112), (111), ({{overline|2}}23), ({{overline|1}}11) and ({{overline|2}}21).<ref name=AM15/> Curved crystals are common.<ref name=Mindat/><ref name=HOM/> The numbers in brackets are [[Miller indices]].


== Appearance ==
== Appearance ==
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== Optical Properties ==
== Optical Properties ==
[[Reflected light anisotropism]] is the property of a material which appears to change colour when viewed under [[crossed polarisers]] in a [[reflected light microscope]]. Fülöppite exhibits moderate reflected light anisotrophism in blue-green to red-brown.<ref name=Mindat/><ref name=Webmin/>
Fülöppite is opaque. A [[petrographic microscope]] can be used to examine opaque materials under reflected [[polarised light]]. Under these conditions the mineral shows moderate [[anisotropic|anisotropism]], changing colour from blue-green to red-brown.<ref name=Mindat/><ref name=Webmin/> The [[reflectivity (optics)|reflectivity]] in air for light of wavelength 540 [[nanometre|nm]] is 31.9% to 40.1%.<ref name=Dana/><ref name=Webmin/>
RL Colour (in reflected plane polarised light) Bronzy white (Webmin), white (Mindat).
The [[reflectivity]] in air for light of wavelength 540 nm is 31.9% to 40.1%.<ref name=Dana/><ref name=Webmin/>


== Physical Properties ==
== Physical Properties ==
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The [[type locality]] is the Dealul Crucii Adit, [[Baia Mare]], Maramureș County, Romania,<ref name=Mindat/> and the type material is kept at the [[Natural History Museum, London]], England, reference 1929,248.<ref name=HOM/>
The [[type locality]] is the Dealul Crucii Adit, [[Baia Mare]], Maramureș County, Romania,<ref name=Mindat/> and the type material is kept at the [[Natural History Museum, London]], England, reference 1929,248.<ref name=HOM/>
It is of [[hydrothermal]] origin and associated with [[zinkenite]], [[semseyite]], [[fizélyite]], [[andorite]], [[freieslebenite]], [[geocronite]], [[boulangerite]], [[jamesonite]], [[cinnabar]], [[sphalerite]], [[marcasite]], [[quartz]] and [[dolomite]].<ref name=HOM/>
It is of [[hydrothermal]] origin and associated with [[zinkenite]], [[semseyite]], [[fizélyite]], [[andorite]], [[freieslebenite]], [[geocronite]], [[boulangerite]], [[jamesonite]], [[cinnabar]], [[sphalerite]], [[marcasite]], [[quartz]] and [[dolomite]].<ref name=HOM/>
Fülöppite was first reported in Britain from Wet Swine Gill, [[Caldbeck]] Fells, Cumbria. It was described as dark grey metallic patches of [[fibrous]] crystals accompanying [[stibnite]]. Subsequently, rare dark red [[resinous]] to [[submetallic]] crystals associated with stibnite were identified as being close to fülöppite in composition. <ref name=><JRS>Journal of the Russell Society 8(2) 101-102></ref>
Fülöppite was first reported in Britain from Wet Swine Gill, [[Caldbeck]] Fells, Cumbria. It was described as dark grey metallic patches of [[Crystal habit|fibrous]] crystals accompanying [[stibnite]]. Subsequently, rare dark red [[Lustre (mineralogy)|resinous]] to [[Lustre (mineralogy)|submetallic]] crystals associated with stibnite were identified as being close to fülöppite in composition. <ref name=><JRS>Journal of the Russell Society 8(2) 101-102></ref>


Name in Other Languages:
Name in Other Languages:

Revision as of 04:07, 2 March 2016

Fülöppite
Fülöppite-572108
Fülöppite from Baia Mare, Romania
General
Categorysulfosalts
Formula
(repeating unit)		Pb3Sb8S15
Strunz classification2/E.21-50 or 2.HC.10a
Dana classification03.06.20.01
Crystal systemMonoclinic [1] 2/m, space group C 2/c
Identification
Formula mass2,076.59 g [2]
ColorLead-gray; may tarnish steel-blue or bronzy white [1]
Crystal habitShort prismatic and pyramidal
FractureUneven [1]
TenacityBrittle
Mohs scale hardness2½
LusterMetallic
Streakreddish grey [1]
DiaphaneityOpaque
Specific gravity5.2
References[3]

[4] [2] [5]

[1]

Fülöppite is a rare member of the plagionite group, comprising other group members are heteromorphite Pb7Sb8S19, plagionite Pb5Sb8S17 and semseyite Pb9Sb8S21.[4] It was named in 1929 for Dr Bela Fülöpp, (1863-1938), a Hungarian lawyer, statesman and mineral collector.[3][4]

Structure

Fülöppite forms a homologous series with other members of the plagionite group. The structures of these minerals differ by the thickness of a galena sheet which occurs in all of them. Fülöppite has the thinnest such sheet.[4]

Crystallography

There are four formula units (Z = 4) per unit cell, and it has sides of lengths a = 13.44 Å, b = 11.73 Å and c = 16.93 Å, with the angle between a and c being β = 94.7°. [3][4][5] Crystals are short prismatic parallel to [201], up to 3 mm long, or pyramidal. They are striated on {100} parallel to [010] and on {112} parallel to [110]. Forms which have been observed include (001), (100), (101), (112), (111), (223), (111) and (221).[1] Curved crystals are common.[4][5] The numbers in brackets are Miller indices.

Appearance

The crystals are short prismatic and pyramidal, with a lead-grey colour that may tarnish to steel-blue or bronze-white.[1] The streak is reddish grey. The crystals are opaque, with a metallic lustre.[4][2]

Optical Properties

Fülöppite is opaque. A petrographic microscope can be used to examine opaque materials under reflected polarised light. Under these conditions the mineral shows moderate anisotropism, changing colour from blue-green to red-brown.[4][2] The reflectivity in air for light of wavelength 540 nm is 31.9% to 40.1%.[3][2]

Physical Properties

The mineral is brittle with an uneven fracture. It is soft, with a Moh's hardness of only 2½, and heavy, with specific gravity 5.2.[4][2][5] It melts easily in an open tube yielding sulphur fumes and a deposit of Sb2S2. It is not attacked by concentrated hydrochloric acid.[1]

Occurrence

The type locality is the Dealul Crucii Adit, Baia Mare, Maramureș County, Romania,[4] and the type material is kept at the Natural History Museum, London, England, reference 1929,248.[5] It is of hydrothermal origin and associated with zinkenite, semseyite, fizélyite, andorite, freieslebenite, geocronite, boulangerite, jamesonite, cinnabar, sphalerite, marcasite, quartz and dolomite.[5] Fülöppite was first reported in Britain from Wet Swine Gill, Caldbeck Fells, Cumbria. It was described as dark grey metallic patches of fibrous crystals accompanying stibnite. Subsequently, rare dark red resinous to submetallic crystals associated with stibnite were identified as being close to fülöppite in composition. [6]

Name in Other Languages: German: Fülöppit Russian:Фюлеппит Simplified Chinese: 柱硫锑铅矿 Spanish: Fülöppita




References

  1. ^ a b c d e f g h <American Mineralogist (1930): 15: 201-202.abstract from Mineral. Mag. (1929) 22: 179-184>
  2. ^ a b c d e f <http://www.webmineral.com/data/Fuloppite.shtml#.VZYMb0am2J8>
  3. ^ a b c d <Gaines et al (1997) Dana’s New Mineralogy, Eighth Edition. Wiley>
  4. ^ a b c d e f g h i j <http://www.mindat.org/min-1559.html>
  5. ^ a b c d e f <http://www.handbookofmineralogy.org<>
  6. ^ <JRS>Journal of the Russell Society 8(2) 101-102>
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