Common. Present in all three oxidation zones.
- 1st Oxidation Zone
- 2nd Oxidation Zone
- 3rd Oxidation Zone
Paragenetic and General Notes
Although siderite is common at Tsumeb, specimen-quality material is rare. Three occurrences of siderite stand out:
(1) Gemmy, yellow, or red-brown scalenohedra and modified rhombohedral crystals, to about 10 mm, on a matrix of massive chalcocite / tennantite ore, from the second oxidation zone.
(2) Brown, or beige-coloured crystals in vugs in germanium-rich sulphide ores accompanying minerals such as ludlockite and stottite, and sometimes resembling the latter. Siderite in this paragenesis typically contains up to 9% zinc and is commonly referred to as zincian siderite.
(3) In the third oxidation zone, on 46 Level, greenish-disc-like crystals of siderite are associated with chalcocite, and samples of this siderite may contains up to 8.5% nickel (Gebhard, 1999).