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Mineral Resources and Geofluids

Introduction to Ore Microscopy

Prof. Lluís Fontboté

(Units A-D) Part 1

Learning to recognize the main properties
for determination of opaque minerals in reflected light microscopy



Property Examples Deposit Unit Photo no
Reflectivity (R%) Reference minerals
carbonates + silicates
(holes + araldit)
Rammelsberg A
Dale Head North A
Color white (reinweiss) gn, as Dale Head North A
gn Rammelsberg A  
weakly colored 
and grey
(wenig farbig)
sl, py, marcasite Dale Head North A
sl, py, marcasite Rammelsberg A  
magnetite Ducktown/Faro B
cp, pyrrhotite Dale Head North B
cp, enargite Rammelsberg B
covellite Yauricocha B
pyrrhotite Ducktown (Chisel) B
Bireflexion only R.% carbonates Rammelsberg B  
R.% + change of color covellite Yauricocha B
pyrrhotite Dale Head North B
pyrrhotite Ducktown/Faro B  
Hardness (relative)
wear resistance (Schleifhärte)
  => polishing scratches (Schleifkratzer)
pull up resistance (Ritzhärte)
  => Kalb fringe (Lichtlinie)
cp, gn vers py, as Dale Head North C
cp, gn vers py Rammelsberg C
sl against mt Faro C  
sl against sulfosalts Wiesloch C  
Internal Reflexions (IR) sl Dale Head North C
sl Wiesloch C
carbonates, silicates Rammelsberg C  
Anisotropy effects
with crossed nichols
marcasite (++) Rammelsberg B
covellite (+++) Yauricocha B
enargite, luzonite (++) Yauricocha B
pyrrhotite (++) Ducktown/Faro B  
  Dale Head North B
arsenopyrite (++) Dale Head North B
cp (+) Dale Head North B
  Rammelsberg B  


[Mineral Resources and Geofluids]  [Ore microscopy]  [Systematic]  [Properties]  [Slides]  [Abbreviations]  [Search for formula at Athena]

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