A soil at the heart of Samar, the third largest island of the Philippine archipelago, and along the Paranas-Taft road at about 300 m above sea level (within the Samar Island Natural Park) easily catches the attention of travellers. This is because it is unique: it is green in color. As far as I know, no soil with such color has yet been reported in the scientific literature.
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| The melanterite soil near the Bagacay mining area in Samar island |
The dominant green color is probably due to the abundance of the secondary mineral called melanterite, a hydrated iron sulphate mineral (FeSO4.7H2O) formed from the decomposition of pyrite or other iron minerals due to the action of surface waters. Melanterite is known to be stable only under highly acidic condition. It is commonly found in mines as a post-mining formation on mine walls, in sulfidic sedimentary and metamorphic rocks as well as in coal and lignite deposits. It indicates the possible presence of sulfuric acid and should not be handled with bare hands or inhaled (www.mindat.org).
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| Photo of the site along the highway in Central Samar where the melanterite soil occurs |
The green soil we have examined in Samar developed from mudstone interlayered with coal deposit. The site is not far from an area which was mined for coal and pyrite and thus it appears to satisfy the environmental conditions favorable for melanterite occurrence.
We had the chance to examine the soil during our fieldwork in Samar on 2-3 Feb 2012 as part of my graduate course in pedology (Soil Science 212). We plan to conduct a detailed pedological and geochemical study on this soil in the near future. For easy reference, I suggest to call it “Samar melanterite soil”.
Recent updates: In the book "Assessment, Restoration and Reclamation of Mining Influenced Soils" edited by Prof. Jaume Bech (University of Barcelona) and his colleagues and published by Academic Press, London, in 2017, the occurrence of melanterite mineral in some mining-affected soils from Spain and Portugal has been mentioned. This seems to confirm our observation about the green soil in Samar in 2012.
Recent updates: In the book "Assessment, Restoration and Reclamation of Mining Influenced Soils" edited by Prof. Jaume Bech (University of Barcelona) and his colleagues and published by Academic Press, London, in 2017, the occurrence of melanterite mineral in some mining-affected soils from Spain and Portugal has been mentioned. This seems to confirm our observation about the green soil in Samar in 2012.
(Members of the team: Ariel Bolledo, Mark Moreno, Pearl Carnice, Richel Lupos, Dr. Ian Navarrete (Humboldt Research Fellow), Forester Elpidio Cabahit Jr. from the Samar Island Natural Park, and myself (VBA)).
That is amazing! Love to hear more about this soil as you do more work on it :D
ReplyDeleteInteresting soil. Thnx for posting.
ReplyDeleteWhy is it in Samar island only? Is it possible to find it in other places in Philippines?
ReplyDeleteIntriguing!
And muse naa unta sa middle, kay charming ra ba he he he. Nice and interesting soil. Sana dumami pa ang mga soil scientists, interesting and ginagawa nila.
ReplyDeleteThank you readers for your visit and for leaving nice words behind.
ReplyDeletesir, wala pa bay nagconduct ug research about hianang soil? can i conduct thesis on it?
ReplyDeleteIt's very interesting and informative! Thanks for the information shared.
ReplyDelete"Soil scientists are getting younger as the soils are getting older".
I'm now on Soil and Environment blog. :-) Good job, Sir Vic. I love the layout. Nindot sa mata ang tanan.
ReplyDeleteThank you very much Dor for your kind comment.I hope readers will find the articles useful. See you and Mark in Stuttgart this summer!
ReplyDelete