Download Yes, we are all star dust. Even Gary!

The Cosmological Source of
Rocks & Minerals
Yes, we are all star dust.
Even Gary!
November 01, 2006
K-W Gem and Mineral Club
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. 25th to Mar. 3rd, 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)
Oxygen
46.5%
Oxygen
85.79%
Nitrogen
78.08%
Silicon
28.0%
Hydrogen
10.67%
Oxygen
20.95%
Aluminum
8.1%
Chlorine
2.07%
Argon
0.93%
Iron
5.1%
Sodium
1.14%
Carbon Dioxide
0.03%
Calcium
3.5%
Magnesium
0.14%
Neon
0.0018%
Sodium
3.0%
All others
0.19%
Helium
0.0005%
Potassium
2.5%
Krypton
0.0001%
Magnesium
2.2%
Hydrogen
0.00005%
Titanium
0.5%
Xenon
0.000008%
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)
Parts of a Solar-type Star
Nuclear Equations
When condensing clouds ignite into thermonuclear
Reactions, around >10^7 K, a star is born!
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:
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.
Hertzsprung
-Russell
Diagram
Subatomic
Particles
In Atoms
Cat’s Eye
Nebula:
A solar-type
star in its
death-throes
Crab
Nebula:
a supernova
The Crab Nebula: a supernova explosion
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
So,
Rock on!
The End 