Fülöppite
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| Fülöppite | |
|---|---|
| General | |
| Category | sulfosalts |
| Formula (repeating unit) | Pb3Sb8S15 |
| Strunz classification | 2/E.21-50 or 2.HC.10a |
| Dana classification | 03.06.20.01 |
| Crystal system | Monoclinic (AM15) 2/m, space group C 2/c (All) |
| Identification | |
| Formula mass | 2,076.59 g (Webmin) |
Member of the Plagionite Group Other Members of Group: Heteromorphite Pb7Sb8S19 Plagionite Pb5Sb8S17 Semseyite Pb9Sb8S21 (Mindat) Named in 1929 for Dr. Bela Fülöpp, (1863-1938) Hungarian lawyer, statesman and mineral collector (Dana, Mindat)
Structure Fülöppite is a rare mineral in a homologous series with heteromorphite, plagionite and semseyite. Their structures differ by the thickness of a galena sheet in the structure. Fülöppite has the thinnest such sheet (Mindat). Unit Cell Parameters: Z = 4 (All) a = 13.44Å, b = 11.73Å, c = 16.93Å β = 94.7° (Dana, Mindat, HOM) a = 16.9, b = 11.69, c = 13.39, beta = 94.72° (Webmin) beta 85o 15.5' (AM15) Crystal habits: Short prismatic and pyramidal (All) Morphology: Crystals short prismatic [201], to 3 mm, and pyramidal; striated on {100} || [0B10] and on{B112} || [110]; curved crystals common (Mindat, HOM). Forms (001), (100), (B101), (112), (111), (B223), (b111), (B221) (AM15)
Colour:Lead-gray; may tarnish steel-blue or bronzy white (AM15, All)
Streak: reddish grey ( AM15, Mindat, Webmin, HOM) grey-black (Dana) Lustre: Metallic (All) Diaphaneity: Opaque (Mindat, Webmin, HOM) RL Anisotropism (the material appears to change colour when viewed under crossed polarised light in a reflected light microscope) RL Anisotrophism: Moderate in blue-green to red-brown (Mindat, Webmin) May be weak in bluish gray, moderate in blue-green to red-brown (HOM), distinctly anisotropic (Dana)
RL Colour (in reflected plane polarised light) Bronzy white (Webmin), white (Mindat).
Reflectivity in air (540 nm): 31.9 – 40.1% (Dana, Webmin), 36.1–42.0% (HOM) Fracture: Uneven (AM15, All except Dana) Tenacity Brittle (All except Dana) Hardness 2½ (All) Specific Gravity measured 5.2, calculated 5.2 (All) Other Characteristics: Fuloppite is not radioactive (Webmin)Melts easily in an open tube yielding sulphur fumes and a deposit of Sb2S2. Not attacked by concentrated hydrochloric acid (AM15) Type Locality: Dealul Crucii Adit (Crucii Hill; Kreuzberg; Kereszthegy), Baia Mare (Nagybánya), Maramureș Co., Romania (Mindat) Type Material: The Natural History Museum, London, England, 1929,248 (HOM).
Occurrence and Associations Of hydrothermal origin (All except Dana).
Association:Zinkenite, semseyite, Fizélyite, andorite, freieslebenite, geocronite, boulangerite,jamesonite, cinnabar, sphalerite, marcasite, quartz, dolomite (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. More recently, rare dark red resinous to submetallic subhedral to euhedral crystals associated with stibnite were identified as being close to fülöppite. (JRS). References: Dana: Gaines et al (1997) Dana’s New Mineralogy, Eighth Edition. Wiley Mindat: http://www.mindat.org/min-1559.html Webmin: http://www.webmineral.com/data/Fuloppite.shtml#.VZYMb0am2J8 HOM: http://www.handbookofmineralogy.org
AM15: American Mineralogist (1930): 15: 201-202. (AM70) Amer. Mineral., 70, 1056–1058. JRS: JRS 8(2) 101-102 Name in Other Languages: German: Fülöppit Russian:Фюлеппит Simplified Chinese: 柱硫锑铅矿 Spanish: Fülöppita