I am a materials science (and metallurgy) student and geology enthusiast. Comparing these two subjects side by side, I have found out some interesting pattern.
Ironmaking slag has 40-45% CaO, 30-40% SiO2 , 10-15% Al2O3 , about 5% MgO and 1-2% FeO. Steelmaking slag can have 40-60% CaO, 10-25% SiO2, 2-10% MgO, 5-35% FeO and 0-25% P2O5.
Ironmaking slag can have, among many other minerals, Akermanite, Monticellite, Gehlenite ,Anorthite, Pyroxene etc, along with some spinels. In my opinion , it matches with some feldspathoids with slightly mafic character. Steelmaking slag is more close to alkaline earth mafic rocks and peridotites. It has a good amount of spinels, monticellite, merwinite, silicocarnite, periclase etc.
Answers from metallurgists and Geologists are welcome
Dear Mr. Bhowmick,
Slags are artificial products representing Fe ore which is made up of the Fe ore mineral and a wide range of gangue from carbonate to silicate minerals (rock) and the slag-producing additives e.g. limestone. The entire process in blast furnace takes place at low pressure and high temperatures. As a consequence of that the natural analogue is a combination of rocks forming at high T and low P which is the mafic volcanic clan (different types of basalt, see e.g. the major mineraloids in slags are Fe-enriched olivine s.s.s., pyroxenoids, wuestite and native elements plus Ca-Mg components). As far as the metamorphic part is concerned the natural equivalent well presenting these conditions is the so-called sanidinite hornfels facies (contact metamorphic reactions of carbonates at low pressure and very high temperature). These processes result in the formation of monticellite, akermanite, melilite, tilleyite, spurrite , rankinite , merwinite and larnite. The pressure conditions are below 1 kbar and the temperature greater than 700°C.
Kind regards
H.G.Dill
Dear Sumit,
although they are relatively rare and 'special' types of rock (and neither igneous nor truly regional metamorphic), you may also be interested in looking up papers that describe impact glasses and fulgurites formed by lightning strike. In both rock-/glass-forming processes the local conditions can be highly reduced. Examples are glasses from Argentina, but also the enigmatic 'Edeowie Glass' found in South Australia and the (also enigmatic) Dakhleh Glass from Egypt. There is good literature on the Formation of fulgurites. Often times those glasses look strikingly similar to industrial and ancient slags. Another potential analog might be the vesicular impact melt rocks and glasses from the basalt-hosted Lonar impact crater in India.
Best,
Martin
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