November 01, 2006K-W Gem and Mineral Club The Cosmological Source of Rocks & Minerals Yes, we are all star dust. Even Gary!
References “Before there was chemistry: The origin of the elements” by Neil Glickstein, online. JChemEd.chem.wisc.edu, Vol. 76 No 3 March 1999. Meteorites, a presentation to the K-W Gem and Mineral Club by Jeffrey Shallit in 2005. Stellar Evolution … http:www.astunit.com/tutorials/stellar.htm The Origin of the Elements, edited by David Alles, Western Washington University, March 13, 2005. online. Wikipedia (online) for Hertzprung-Russell diagram Waving at the neighbours, the search for extra-terrestrial life. The Economist, Feb. 25 th to Mar. 3 rd, 2006.
And in the beginning there was … … a singularity. Suddenly there was a Big Bang … which included a massive Inflation within trillionths of a second … Meanwhile, back to the future, we have Earth …
Elements Found in the Earth's Crust, Ocean and Atmosphere Earth's Crust (by mass)Oceans (by mass)Atmosphere (volume of dry air) Oxygen46.5%Oxygen85.79%Nitrogen78.08% Silicon28.0%Hydrogen10.67%Oxygen20.95% Aluminum8.1%Chlorine2.07%Argon0.93% Iron5.1%Sodium1.14%Carbon Dioxide0.03% Calcium3.5%Magnesium0.14%Neon0.0018% Sodium3.0%All others0.19%Helium0.0005% Potassium2.5%Krypton0.0001% Magnesium2.2%Hydrogen0.00005% Titanium0.5%Xenon0.000008% Yikes! Chemistry!
Observed abundance of baryonic matter: ~ 73% H ~ 25% He < 2% all other
Basic Origin of Elements 4 main sources: Primordial Nucleosynthesis (Big Bang) = Hydrogen, Deuterium, Helium and some Lithium Small Stellar Nucleosynthesis (fusion in Solar-type Stars) = more Helium … plus Beryllium, Boron and Carbon … As carbon life-forms, we are indeed star dust! Massive Stellar Nuc. (fusion in massive stars) = Oxygen to Iron Supernovae (exploding massive stars) = all other naturally occurring elements heavier than Iron (ie the metals and rare earths)
Nuclear Equations Huge numbers of protons (H) are fused in our Sun by the following process every second: At temperatures exceeding 10^8 K, helium nuclei will fuse to form carbon: Subsequently, carbon and helium react to form oxygen: With increasing temperatures in the core of the star, heavier elements form: When condensing clouds ignite into thermonuclear Reactions, around >10^7 K, a star is born!
Life Cycle of Stars Stars condense from “birthing” nebulae and die as “funerary” nebulae. The “life steps” taken depend on the mass of the star: 0.1 – 1.4 solar masses = condense, main sequence star of Hertzprung-Russell Diagram (ie like our Sun). Core condenses and outer layers expand to a giant star, possible nebula, ending as white dwarf. 1.4 – 8.0 = much faster version of above, core includes iron and implodes, which is followed by a large rebound explosion (supernova) > 8.0 = same as above, much faster, but implosion does not end as explosion. Instead it keeps collapsing and becoming denser until a black hole is formed.
Cat’s Eye Nebula: A solar-type star in its death-throes
The Crab Nebula: a supernova explosion Crab Nebula: a supernova
Basic Elements that Geologists Love? Hydrogen and Helium are core to our natural gases Carbon can be manifested as coal, graphite and diamonds … or as geologists! Oxygen shows up as water, ice (key to Quaternary studies), Ilmenite, titanium oxides etc. Sulphur underlies our many sulphates Magnesium can be found in Olivine Iron is broadly represented within base metal ores, pyrite, and like other elements, as interstitial atoms in silicates and other minerals
Some Earth-bound Evidence of Cosmological Origins? (Thank you Jeff!) Meteorites! – Stony, Stony-Iron and Iron types Iron meteorites are thought to be cores of asteroids Stony-Iron are thought to be a mixture of core and mantle of asteroids Achondrites may come from crust and upper mantle of asteroids