Iron in Hawaiian Islands
Date: Summer 2013
I taught Hawaiian history for the last few years and all of the texts say that there is no iron on the Hawaiian Islands. Recently, I wondered about the red cinder that is on the Big Island - is it red because of iron? If red cinder does have iron, can it be extracted?
The statement that there is no iron on Hawaii is not quite correct. Iron is the fourth most abundant element on the Earth's crust and it is dispersed throughout Earth's entire surface. I have found some data that states that about one-tenth of Hawaiian basalt is iron oxide. What is true, though, is that environmental conditions in Hawaii has not resulted in the *concentration* of iron into large enough ore deposits so that some kind of mining and smelting -even in small scale- can be viable. This is likely due to the fact that, although the islands are volcanic and volcanic activity along with erosion should concentrate metals into ores, the relative youth of the islands in geological time has not allowed for the ores to well up or concentrate.
Cinder is mostly silicon oxides, the red tinge may be iron (I can't find data on it) but even so, the amounts of iron in that will be so small as to make smelting impractical.
Greg (Roberto Gregorius)
Hawaii has iron, just not in a readily available form. The basalt is oxidized in air to form the red cinder as Fe2O3-nH2O, rust. There is at least 15 - 20% iron in the cinder matrix.
The Fe may be extracted using crushed cinder-HCl to form FeCl3, precipitated using NaOH, filtered and followed with smelting into pig iron. Brasted, Robert C. J. Chem. Educ. 1970, 47, 634; is a paper that talks to the availability of Fe in Hawaiian volcanic rock. The yield of Fe is low, but as a middle school experiment, it would demonstrate many aspects of chemistry along with an excursion into geochemistry!
Hoping this helps! Peter E. Hughes, Ph.D. Milford, NH
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