Abstract
Samples from the Pb-Zn-Cu skarns of M. Ci-villina (Italy), Valle del Temperino (Italy), and Empire Mine (New Mexico, USA) have been analysed for their pyroxenes and pyroxenoids. The samples were collected immediately adjacent to the marble-skarn replacement front. All contain manganiferous pyroxenoids and manganeserich Ca-pyroxenes. The pyroxenes from each deposit form distinct groups of compositions within the diopside-hedenbergite-johannsenite triangle, with no apparent miscibility gap. Diopside contents usually are below 15 mole percent. Fibrous bustamite occurs as monomineralic zones in the Empire and in the Temperino deposit. Although rhodonite may be a primary phase in some samples from the Empire Mine, it is commonly of secondary origin in the Empire Mine and in the Civillina deposit. Its formation from manganiferous clinopyroxenes is either due to increasing Mn activity in the hydrothermal skarn solution or to higher X(CO2) in the vapour phase. When rhodonite is formed within clinopyroxenes as submicroscopic lamellae that eventually replace the whole host crystal, resulting compositions lie in the miscibility gap between rhodonite and bustamite. Textural relations indicate the replacement reaction: johannsenite + CO2 = rhodonite + calcite + quartz. Equilibrium temperatures for this reaction have been calculated by using estimated thermochemical data for johannsenite, giving a T(eq)=385° C for X(CO2)=0.1 at P(tot)= 1 kbar. Taking into consideration the reduced activity of Mn in rhodonite and of Ca in calcite, both buffered by the johannsenite, the temperature is increased for about 15° C at X(CO2)=0.01. At lower temperatures, where johannsenite is stable, the X(CO2) is confined to values below 0.01. Despite the mineralogical similarities of the three deposits differences in the development of the manganiferous skarns can be depicted.
Similar content being viewed by others
References
Abrecht J (1980) Stability relations in the system CaSiO3-CaMn-Si2O6-CaFeSi2O6. Contrib Mineral Petrol 74:253–260
Abrecht J, Peters T (1980) The miscibility gap between rhodonite and bustamite along the join MnSiO3-Ca0.60 Mn0.40 SiO3. Contrib Mineral Petrol 74:261–269
Allen VT, Fahey JJ (1953) Rhodonite, johannsenite, and ferroan johannsenite at Vanadium, New Mexico. Am Mineral 38:883–890
Allen VT, Fahey JJ (1957) Some pyroxenes associated with pyrometasomatic zinc deposits in Mexico and New Mexico. Geol Soc Am Bull 63:881–896
Aloisi P (1926) Osservazioni sui pirosseni di Campiglia Marittima (Toscana). Mem Acad Naz Lincei, Classe Sci Fis Mat Nat 2:2–15
Angel RJ (1984) The experimental determination of the johannsenite-bustamite equilibrium inversion boundary. Contrib Mineral Petrol 85:272–278
Appleman DE, Evans HT (1973) Job 9214: Indexing and least squares refinement of powder diffraction data. US Dept Commerce, Natl Tech Inform Serv PB 216
Barbieri G, De Vecchi G, De Zanche V, Di Lallo E, Frizzo P, Mietto P, Sedea R (1980) Note illustrative della carta geologica dell'area di Recoaro. Mem Scienze Geol 34:23–52
Bertolani M (1958) Osservazioni sulle mineralizzazioni metallifere del Campigliese (Livorno). Per Mineral 27:311–344
Brown PE, Essene EJ, Peacor DR (1980) Phase relations inferred from field data for Mn pyroxenes and pyroxenoids. Contrib Mineral Petrol 74:417–425
Burt DM (1974) Metasomatic zoning in Ca-Fe-Si exoskarns. Carnegie Inst Washington Pub 634:287–293
Burt DM (1977) Mineralogy and petrology of skarn deposits. Soc Italiana Mineral Petrol Rendiconti 33:859–873
Burton JC, Taylor LA, Chou I (1982) The \(f_{{\text{O}}_{\text{2}} } - T{\text{ and }}f_{{\text{O}}_{\text{2}} } - T\) stability relations of hedenbergite and of hedenbergite-johannsenite solid solutions. Econ Geol 77:764–783
Corsini F, Cortecci G, Leone G, Tanelli G (1980) Sulfur isotope study of the skarn-(Cu-Pb-Zn) sulfide deposit of Valle del Temperino, Campiglia Marittima, Tuscany, Italy. Econ Geol 75:83–96
Einaudi MT, Meinert LD, Newberry RJ (1981) Skarn deposits. Econ Geol, 75th Anniversary Volume:317–391
Giannini E (1955) Geologia dei monti di Campiglia Marittima (Livorno). Soc Geol Italiana Boll 74:219–296
Helgeson HC, Delany JM, Nesbitt HW, Bird DK (1978) Summary and critique of the thermodynamic properties of rock-forming minerals. Am J Sci 278 A:1–229
Hernon RM, Jones WR (1968) Ore deposits of the Central Mining district, Grant County, New Mexico, in Ridge JD, ed, Ore deposits of the U.S., 1933–1967, (Graton-Sales volume). New York, Am Inst Mining Metall Petroleum Engineers:1211–1238
Hofmann A (1972) Chromatographic theory of infiltration metasomatism and its application to feldspars. Am J Sci 272:69–90
Jones WR, Hernon RM, Moore SL (1967) General geology of Santa Rita quadrangle, Grant County, New Mexico. US Geol Survey Prof Paper 555
Korzhinskii DS (1970) Theory of metasomatic zoning. Clarendon Press, Oxford
Maresch W, Mottana A (1976) The pyroxmangite-rhodonite transformation for the MnSiO3 composition. Contrib Mineral Petrol 55:69–79
Meinert LD (1983) Variability of skarn deposits: Guides to exploration. In: Boardman SJ (ed) Revolution in the earth sciences — Advances in the past half-century. Iowa, Kepdall/Hunt
Meinert LD, Newberry R, Einaudi MT (1980) An overview of tungsten, copper and zinc-bearing skarns in western North America. US Geol Survey Open File Rept 81–355:303–327
Meinert LD, Hawksworth MA (1983) Fluid inclusion composition and temperature evolution in a zoned skarn system, Groundhog Mine, New Mexico. Geol Soc Am Abstr 15:642
Momoi H (1964) Johannsenite from Teragochi, Okayama Prefecture, Japan. Mem Faculty Sci, Kyushu Univ, Series D, Geol 15:65–72
Peters T, Trommsdorff V, Sommerauer J (1978) Manganese pyroxenoids and carbonates. Critical phase relations in metamorphic assemblages from the alps. Contrib Mineral Petrol 66:383–388
Rose AW, Burt DM (1979) Hydrothermal alteration. In: Barnes HL (ed) Geochemistry of hydrothermal ore deposits. New York, Wiley
Schiavinato G (1953) Sulla johannsenite dei giacimenti a silicate manganesiferi del Monte Civillina presso Recoaro (Vicenza) Rend Soc Ital Mineral Petrol 9:3–11
Schmitt H (1939) The Pewabic Mine. Geol Soc Am Bull 50:777–818
Schwander H, Gloor F (1980) Zur quantitativen Mikrosondenanalyse von geologischen Proben mittels kombiniertem EDS/WDS. X-Ray Spectrometry 9:134–137
Tanelli G (1977) I giacimenti a skarn della Toscana. Rend Soc Ital Mineral Petrol 33:875–903
Tardy Y, Garreis RM (1977) Prediction of Gibbs energies of formation of compounds from the elements. II Monovalent and divalent metal silicates. Geochim Cosmochim Acta 41:87–92
Taylor BE, Liou JG (1978) The low-temperature stability of andradite in C-O-H fluids. Am Mineral 63:378–393
Tokunaga M (1965) On the zoned skarn including bustamite, ferroan johannsenite, and manganoan hedenbergite from Nakatatsu Mine, Fukui Prefecture, Japan. Tokyo Kyoika Diagaku Sci Rept, Sec C 9:67–87
Vieillard P (1982) Modèle de calcul des énergies de formation des mineraux, bâti sur la connaissance affinée des structures cristallines. Mem Sci Geol 69
Winter GA, Essene EJ, Peacor DR (1981) Carbonates and pyroxenoids from the manganese deposit near Bald Knob, North Carolina. Am Mineral 66:278–289
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Abrecht, J. Manganiferous pyroxenes and pyroxenoids from three Pb-Zn-Cu skarn deposits. Contrib Mineral and Petrol 89, 379–393 (1985). https://doi.org/10.1007/BF00381559
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00381559