Iddingsite - MgO * Fe2O3 * 4 H2O

Named by Andrew Cowper Lawson in 1893 for one of the great American petrologists Joseph Paxson Iddings. Iddingsite is a common alteration of Olivine during oxidation, hydrothermal and deuteric processes. It appear as a reddish-brown replacement of olivine. Iddingsite is a pseudomorph, and during the alteration process the olivine crystals had their internal structure or chemical composition changed, although the external form has been preserved. The chemical formula for iddingsite has been approximated as MgO * Fe2O3 * 4 H2O where CaO can be substituted by MgO. The alteration of olivine to iddingsite occurs in a highly oxidizing environment under low pressure and at intermediate temperatures.

Bibliography



• E. WM. Heinrich (1956): Microscopic Petrografy. Mcgraw-hill book company,inc
• David Shelley (1983): Igneous and metamorphic rocks under the microscope. Campman & Hall editori.
• Vernon, R. H. & Clarke, G. L. (2008): Principles of Metamorphic Petrology. Cambridge University Press
• Shelley D (1992): Igneous and Metamorphic Rocks under the Microscope: Classification, textures, microstructures and mineral preferred orientation
• Cox et al. (1979): The Interpretation of Igneous Rocks, George Allen and Unwin, London.

Photo
patagonia(3).jpg

Olivine altered by Iddingsite, Patagonia. PPL image, 2x (Field of view = 7mm)
patagonia(4).jpg

Olivine altered by Iddingsite, Patagonia. PPL image, 2x (Field of view = 7mm)
patagonia(5).jpg

Olivine altered by Iddingsite, Patagonia. PPL image, 2x (Field of view = 7mm)
iddingsitee(2).jpg

Olivine partially altered by Iddingsite. PPL image, 2x (Field of view = 7mm)
iddingsitee(3).jpg

Olivine partially altered by Iddingsite. XPL image, 2x (Field of view = 7mm)
iddingsitee(4).jpg

Olivine partially altered by Iddingsite. PPL image, 10x (Field of view = 2mm)
iddingsitee(4).jpg

Olivine partially altered by Iddingsite. XPL image, 10x (Field of view = 2mm)
olivinaalterata175(2).jpg

Olivine partially altered by Iddingsite. PPL image, 10x (Field of view = 2mm)
olivinaalterata175(3).jpg

Olivine partially altered by Iddingsite. XPL image, 10x (Field of view = 2mm)
ioolivinaiddingsinata(2).jpg

Olivine partially altered by Iddingsite. PPL image, 10x (Field of view = 2mm)
ioolivinaiddingsinata(3).jpg

Olivine partially altered by Iddingsite. XPL image, 10x (Field of view = 2mm)
ioolivinaiddingsinata(4).jpg

Olivine partially altered by Iddingsite. PPL image, 10x (Field of view = 2mm)
ioolivinaiddingsinata(5).jpg

Olivine partially altered by Iddingsite. XPL image, 10x (Field of view = 2mm)
ioolivinaiddingsinata(6).jpg

Olivine partially altered by Iddingsite. XPL image, 10x (Field of view = 2mm)
ioolivinaiddingsinata(7).jpg

Olivine partially altered by Iddingsite. PPL image, 10x (Field of view = 2mm)
ioolivinaiddingsinata(8).jpg

Olivine crystals altered by Iddingsite. XPL image, 10x (Field of view = 2mm)
ioolivinaiddingsinata(9).jpg

Olivine crystals altered by Iddingsite. PPL image, 10x (Field of view = 2mm)
ioolivinaiddingsinata(10).jpg

Olivine crystals altered by Iddingsite. XPL image, 10x (Field of view = 2mm)
ioolivinaiddingsinata(11).jpg

Olivine crystals altered by Iddingsite. PPL image, 10x (Field of view = 2mm)
ioolivinaiddingsinata(12).jpg

Olivine crystals altered by Iddingsite. XPL image, 10x (Field of view = 2mm)
ioolivinaiddingsinata(13).jpg

Olivine crystals altered by Iddingsite. PPL image, 10x (Field of view = 2mm)
ioolivinaiddingsinata(14).jpg

Olivine crystals altered by Iddingsite. XPL image, 10x (Field of view = 2mm)
ioolivinaiddingsinata(15).jpg

Olivine crystals altered by Iddingsite. PPL image, 10x (Field of view = 2mm)
ioolivinaiddingsinata(16).jpg

Olivine crystals altered by Iddingsite. XPL image, 10x (Field of view = 2mm)
iddingsite2013d(2).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)
iddingsite2013d(3).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)
iddingsite2013d(4).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)
iddingsite2013d(5).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)
iddingsite2013d(6).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)
iddingsite2013d(7).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). XPL image, 2x (Field of view = 7mm)
iddingsite2013d(8).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)
iddingsite2013d(9).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)
iddingsite2013d(10).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)
iddingsite2013d(11).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)
iddingsite2013d(12).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)
iddingsite2013d(13).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)
iddingsite2013d(14).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)
basaltoalcalinoiddingsite0287(2).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)
basaltoalcalinoiddingsite0287(3).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)
basaltoalcalinoiddingsite0287(4).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)
basaltoalcalinoiddingsite0287(5).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)
basaltoalcalinoiddingsite0287(6).jpg

Olivine crystals altered by Iddingsite. Somalia (Africa). PPL image, 2x (Field of view = 7mm)