| Pyromorphite | |
|---|---|
 | |
| General | |
| Category | Phosphate mineral Apatite group |
| Formula (repeating unit) | Pb5(PO4)3Cl |
| IMA symbol | Pym[1] |
| Strunz classification | 8.BN.05 |
| Crystal system | Hexagonal |
| Crystal class | Dipyramidal (6/m) (same H-M symbol) |
| Space group | P63/m |
| Identification | |
| Color | Dark green to grass-green or green, yellow, yellow-orange, reddish orange, yellow-brown, greenish-yellow or yellowish-green, shades of brown, tan, grayish, white and may be colorless; colourless or faintly tinted in transmitted light. |
| Crystal habit | Prismatic to acicular crystals, globular to reniform |
| Twinning | Rarely on {1122} |
| Cleavage | Imperfect- [1011] |
| Fracture | Uneven to sub-conchoidal |
| Tenacity | Brittle |
| Mohs scale hardness | 3.5–4 |
| Luster | Resinous to subadamantine |
| Streak | White |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 7.04 measured, 7.14 calculated |
| Optical properties | Uniaxial (−) May be anomalously biaxial (−) |
| Refractive index | nω = 2.058 nε = 2.048 |
| Birefringence | δ = 0.010 |
| Pleochroism | Weak |
| Ultraviolet fluorescence | May fluoresce yellow to orange under LW and SW UV |
| Other characteristics | Piezoelectric if biaxial |
| References | [2][3][4] |
Pyromorphite is a mineral species composed of lead chlorophosphate: Pb5(PO4)3Cl, sometimes occurring in sufficient abundance to be mined as an ore of lead. Crystals are common, and have the form of a hexagonal prism terminated by the basal planes, sometimes combined with narrow faces of a hexagonal pyramid. Crystals with a barrel-like curvature are not uncommon. Globular and reniform masses are also found. It is part of a series with two other minerals: mimetite (Pb5(AsO4)3Cl) and vanadinite (Pb5(VO4)3Cl), the resemblance in external characters is so close that, as a rule, it is only possible to distinguish between them by chemical tests. They were formerly confused under the names green lead ore and brown lead ore (German: Grünbleierz and Braunbleierz).
The phosphate was first distinguished chemically by M. H. Klaproth in 1784,[5][6][7][8] and it was named pyromorphite by J. F. L. Hausmann in 1813.[9][10] The name is derived from the Greek for pyr (fire) and morfe (form) due to its crystallization behavior after being melted.[3]
Paecilomyces javanicus is a mold collected from a lead-polluted soil that is able to form biominerals of pyromorphite.[11]
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ Handbook of Mineralogy (PDF).
- ^ a b "Pyromorphite". Webmineral data.
- ^ "Pyromorphite". Mindat.org.
- ^ Klaproth (1784). Von dem Wassereisen, als einem mit Phosphorsäure verbundenen Eisenkalke (in German).
On hydrosiderum [i.e., iron phosphide, Fe2P] as a calcined [i.e., roasted] iron [that is] bonded with phosphoric acid), Chemische Annalen für die Freunde der Naturlehre …, 1 (5) : 390–399. From p. 394: After remarking that lead ores that contain phosphorus can be treated with strong acids to produce phosphoric acid, Klaproth notes that: " … wie solches zuerst Hr. Gahn in Schweden entdeckt, ich selbst aber bey Unersuchung des krystallisirten grünen Bleyerzes von der heil. Dreyfaltigkeit zu Zschopau bestätigt gefunden habe." ( … as such Mr. Gahn in Sweden first discovered, I myself, however, have found [to be] confirmed by investigation of the crystallized green lead ore [i.e., pyromorphite] from the Holy Trinity at Zschopau in Germany]
- ^ Details of Klaproth's chemical analysis of pyromorphite appear in: Klaproth (1785) "Ueber die Phosphorsäure im Zschopauer grünen Bleyspathe" (On phosphoric acid in green lead spar from Zschopau), Beyträge zu den chemischen Annalen, 1 (1) : 13–21.
- ^ LXXXVII. Chemische Untersuchung der phosphorsauren Bleierze: I. Zeisiggrünes Bleierz von Zschopau. (87. Chemical investigation of the lead ores [containing] phosphoric acid: I. Siskin-green lead ore from Zschopau) in: Klaproth, Martin Heinrich, Beiträge zur chemischen Kenntnis der Mineralkörper [Contributions to our chemical knowledge of minerals]. Vol. 3. Posen, (Germany): Decker und Co.; Berlin, Germany: Heinrich August Rottmann. 1802. pp. 146–153.
- ^ Dr. Thomas Witzke. "Entdeckung von Pyromorphit (Discovery of pyromorphite)" (in German).
- ^ Hausmann, Johann Friedrich Ludwig (1813). Handbuch der Mineralogie. Göttingen, Germany: Vandenhoeck und Ruprecht. pp. 1090–1093.
- ^ Chester, Albert Huntington (1896). A Dictionary of the Names of Minerals Including Their History and Etymology. New York, New York: John Wiley & Sons. p. 224.
- ^ Young Joon Rheea; Stephen Hillier; Helen Pendlowskic; Geoffrey Michael Gadd (October 2014). "Fungal transformation of metallic lead to pyromorphite in liquid medium". Chemosphere. 113: 17–21. Bibcode:2014Chmsp.113...17R. doi:10.1016/j.chemosphere.2014.03.085. PMID 25065784.