File:GCPNN019 Chocolate Pot & Gibbon River (14 June 2023) 1.jpg

English: (downstream is to the left)

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Chocolate Pots is a cluster of hot springs along the Gibbon River in Yellowstone, Wyoming (= 44° 42’ 35.87” North latitude, 110° 44’ 32.94” West longitude). They are located north of Paintpot Hill and west of the southern end of Norris Geyser Basin. The largest feature is a brownish-yellowish-reddish-blackish mound on the northwestern bank of the Gibbon River. This mound is designated "GCPNN019" in the RCN database. The mound is composed of "ferrous sinter" or "ferric sinter", which refers to an iron oxide-dominated mineral buildup. Published research has shown that the material is fine-grained, siliceous 2-line ferrihydrite, which is a poorly-crystalline hydrous iron oxide mineral that has an x-ray diffraction pattern with two peaks. The ferrihydrite is mixed with some silica. Hot water emerging from GCPNN019's summit vent has been measured to between 51 and 54 degrees Celsius (= about halfway between the freezing point and the boiling point of pure water). The pH ranges from 5.5 to 6.0 (slightly acidic). Culturing studies and biomarker analysis has shown that numerous specific types of microbes are present at GCPNN019 (see Parenteau et al., 2014 and Fortney et al., 2016).

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References cited:

Parenteau et al. (2014) - Production and early preservation of lipid biomarkers in iron hot springs. Astrobiology 14: 502-521.

Fortney et al. (2016) - Microbial Fe(III) oxide reduction potential in Chocolate Pots hot spring, Yellowstone National Park. Geobiology 14: 255-275.