Fülöppite
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| Fülöppite | |
|---|---|
 Fülöppite from Baia Mare, Romania | |
| 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) |
| Color | Lead-gray; may tarnish steel-blue or bronzy white (AM15, All) |
| Crystal habit | Short prismatic and pyramidal (All) |
| Fracture | Uneven (AM15, All except Dana) |
| Tenacity | Brittle (All except Dana) |
| Mohs scale hardness | 2½ (All) |
| Luster | Metallic (All) |
| Streak | reddish grey ( AM15, Mindat, Webmin, HOM) grey-black (Dana) |
| Diaphaneity | Opaque (Mindat, Webmin, HOM) |
| Specific gravity | 5.2 (All) |
Keep current Fülöppite is a rare member of the Plagionite Group; other group members are heteromorphite Pb7Sb8S19, plagionite Pb5Sb8S17 and semseyite Pb9Sb8S21 (Mindat). It was named in 1929 for Dr Bela Fülöpp, (1863-1938), a Hungarian lawyer, statesman and mineral collector (Dana, Mindat).
Structure
Fülöppite forms a homologous series with other members of the plagionite group. Their structures of these minerals differ by the thickness of a galena sheet which occurs in all of them. Fülöppite has the thinnest such sheet (Mindat).
Crystallography
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) 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)
Appearance
Crystal habits: Short prismatic and pyramidal (All) 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)
Optical Properties
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)
Physical Properties
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)
Occurrence
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.abstract from Mineral. Mag. (1929) 22: 179-184. JRS: JRS 8(2) 101-102 Name in Other Languages: German: Fülöppit Russian:Фюлеппит Simplified Chinese: 柱硫锑铅矿 Spanish: Fülöppita