Gold in irish coal: Palaeo-concentration from metalliferous groundwaters

Liam A. Bullock*, John Parnell, Joseph G.T. Armstrong, Magali Perez, Sam Spinks

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Gold grains, up to 40 μm in size and containing variable percentages of admixed platinum, have been identified in coals from the Leinster Coalfield, Castlecomer, SE Ireland, for the first time. Gold mineralisation occurs in sideritic nodules in coals and in association with pyrite and anomalous selenium content. Mineralisation here may have reflected very high heat flow in foreland basins north of the emerging Variscan orogenic front, responsible for gold occurrence in the South Wales Coalfield. At Castlecomer, gold (–platinum) is attributed to precipitation with replacive pyrite and selenium from groundwaters at redox interfaces, such as siderite nodules. Pyrite in the cores of the nodules indicates fluid ingress. The underlying Caledonian basement bedrock is mineralised by gold, and thus likely provided a source for gold. The combination of the gold occurrences in coal in Castlecomer and in South Wales, proximal to the Variscan orogenic front, suggests that these coals along the front could comprise an exploration target for low-temperature concentrations of precious metals.

Original languageEnglish
Article number635
Number of pages15
JournalMinerals
Volume10
Issue number7
DOIs
Publication statusPublished - 17 Jul 2020

Keywords

  • Coal
  • Gold
  • Groundwater
  • Ireland
  • Platinum
  • Pyrite
  • Siderite
  • Variscan orogeny
  • SOUTH WALES COALFIELD
  • MIGRATION
  • siderite
  • BROWN COALS
  • ALLUVIAL GOLD
  • METAMORPHISM
  • groundwater
  • pyrite
  • gold
  • MASSIF
  • platinum
  • CALEDONIDES
  • MINERALIZATION
  • coal
  • BASIN
  • GEOCHEMISTRY

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