<p>I'll second &quot;AtmosphericPrisonEscape&quot; 's request for more info about these &quot;<em>ur</em> minerals&quot;. I've never heard the term (though I can parse it from the common German description of <em>Archaeopteryx</em> as &quot;Der <em>Ur</em>-vogel&quot;).</p>
<p>Hazen is (or was) at the Carnegie Institute of Geo-something, working on high-pressure mineralogy etc. So I'm going to suspect his &quot;<em>ur</em> minerals&quot; are likely to be the ones that form in a magma of &quot;typical&quot; planetary composition. (There's a lot of detail in that &quot;typical&quot; ; lots of good &quot;three beer&quot; arguments to be had there.) But leaving that aside, for the commonest terrestrial-planet minerals I'd look at olivines (Mg- and Fe-, forsterite and fayalite), pyroxenes (ortho- and clino-, &quot;OPX&quot; and &quot;CPX&quot; in the jargon), feldspars (Ca-, Na- and K- bearing ; anorthite, albite and orthoclase), silica (quartz), pyrite (iron sulphide), metallic iron (with nickel) and something hydrous, so let's say a mica. That's 11 minerals. Something else needed for the round dozen.</p>
<p>But then it starts to get complicated. In around half of Earth's (or Venus') volume, the olivine would be unstable compared to a mineral called ringwoodite (which could soak up most of the water fraction in the mica - easily 0.25 % by mass (Earth is about 0.1% water by mass) ; but Mars, given the same proportion of elements would have almost no ringwoodite becasue it's too small. Mercury is smaller. I'm sure Hazen knows this (I think his institution measured the water-absorption of ringwoodite at lower-mantle conditions, if not himself personally). Which is why we'd really need Hazen's actual list of &quot;<em>ur</em>-minerals&quot;.</p>
<p>Is that species count &quot;low&quot; for an early solar system? I don't think so, IF (big <strong>IF</strong>) we're talking about the mantle/ upper core chemistry. Those minerals, with their various solid solutions between end members and minor substitutions (e.g. titanium substituting for iron in the sulphide and pyroxene phases) will cover ... 95% plus of the atoms in the planet. Maybe 99%.</p>
<p><strong>BUT</strong> if he's talking about the near surface, where the water gathers, temperatures are low, and potentially life can form (I know Hazen has drifted from the One True Path of Mantle Petrology into biology in the last decades), then yes, you get into literally thousands of &quot;clay&quot; minerals alone. Whole families of amphiboles also competing to get their atoms wet. Dozens of micas (I was thinking of biotite, probably the most thermally stable of the family) ...</p>
<blockquote>
<p>Wouldn't it be prudent to explore the idea that Earth was might already have had more complex molecules in the &quot;soup&quot; than just the twelve &quot;ur minerals?&quot;</p>
</blockquote>
<p>Sounds like you're thinking about the biological end of things. Wet end certainly. So yes, the minerals would be much more complex at the surface. Poke them barely 100km below the surface (my mantle Petrology lecturer used to refer to anything within 100km of the surface as &quot; <em>crustal ephemera</em> ; nowhere near equilibrium, and safe to ignore. Except for it's confining pressure - that's useful.&quot;) and they'll revert to those dozen-ish minerals I listed. It might take a hundred million years or so (1/45th of the age of any of the planets), but they'd revert to a mixture of those minerals with all the haste of a rock reading a thermodynamic equilibrium equation.</p>
<p>But near the surface, you can ignore all those minerals on my list, and just replace the whole lot with some generic &quot;octahedral&quot; and &quot;tetrahedral&quot; sheets from phyllosilicates (micas, the whole motley crew of clay mineral families) without caring that much about the labile (easily altered) cations and hydroxyl ions scattered around the sheet edges and between the sheet overlaps. Lots of interesting stuff there - I saw Alan Cairns-Smith lecture on his &quot;Origin Of Life via clay minerals&quot; book tour when I was an undergraduate. But the details of the mineralogy don't matter much - and I say that with &quot;Mineralogy&quot; in my BSc title, and a course unit in Soil Science where the <em>right</em> species of clays are really significant.</p>
<p>Does Hazen discuss this &quot;<em>ur</em> mineral&quot; concept online anywhere? I've brought his books in the past, and don't feel strongly inclined to do it again. Published papers are better value for money.</p>

CC BY-SA 4.0
2024-11-21T04:31:17.447Z
2024-11-21T04:31:17.447Z
Rockdoctor
<p>I am fascinated by Hazen's work on mineral evolution, but I am wondering if I am overlooking something, as it seems as though the twelve species of &quot;ur minerals&quot; is a low estimate for a solar system with a Population I star. If stars were coming and going for nine billion years, wouldn't it make more sense that the mineral diversity would have been greater, perhaps explaining the relatively rapid abiogenesis event that occured after Earth's accretion? Wouldn't it be prudent to explore the idea that Earth was might already have had more complex molecules in the &quot;soup&quot; than just the twelve &quot;ur minerals?&quot;</p>

CC BY-SA 4.0
2024-11-06T23:37:43.663Z
Can you link some reading about those "ur minerals"? While the origin of life is hardly only about minerals (liquids and gases play their crucial roles too), how we in the planet formation community typically think about mineral formation is in the context of the "condensation sequence", i.e. as a solar metallicity (i.e. Pop I) gas cools down from several 10^3 Kelvin, what's the sequence of minerals that form? The answer can be found in diagrams like this https://www.planetary.org/space-images/condensation-sequence  which are calculated based on the partitioning thermodynamics.
AtmosphericPrisonEscape
<minerals>
Does the sun being a Population I star have an effect on theories of mineral evolution?
blacktopshaman
# Does the sun being a Population I star have an effect on theories of mineral evolution?

(Asked by: username_0 on 2024-11-06)

I am fascinated by Hazen's work on mineral evolution, but I am wondering if I am overlooking something, as it seems as though the twelve species of "ur minerals" is a low estimate for a solar system with a Population I star. If stars were coming and going for nine billion years, wouldn't it make more sense that the mineral diversity would have been greater, perhaps explaining the relatively rapid abiogenesis event that occured after Earth's accretion? Wouldn't it be prudent to explore the idea that Earth was might already have had more complex molecules in the "soup" than just the twelve "ur minerals?"

**Tags:** minerals

> **Comments:**
> **username_1**: Can you link some reading about those "ur minerals"? While the origin of life is hardly only about minerals (liquids and gases play their crucial roles too), how we in the planet formation community typically think about mineral formation is in the context of the "condensation sequence", i.e. as a solar metallicity (i.e. Pop I) gas cools down from several 10^3 Kelvin, what's the sequence of minerals that form? The answer can be found in diagrams like this https://www.planetary.org/space-images/condensation-sequence  which are calculated based on the partitioning thermodynamics.  

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## 1 answers

### Answer by username_2 on 2024-11-21. Score: 0

I'll second "username_1" 's request for more info about these "*ur* minerals". I've never heard the term (though I can parse it from the common German description of *Archaeopteryx* as "Der *Ur*-vogel").

Hazen is (or was) at the Carnegie Institute of Geo-something, working on high-pressure mineralogy etc. So I'm going to suspect his "*ur* minerals" are likely to be the ones that form in a magma of "typical" planetary composition. (There's a lot of detail in that "typical" ; lots of good "three beer" arguments to be had there.) But leaving that aside, for the commonest terrestrial-planet minerals I'd look at olivines (Mg- and Fe-, forsterite and fayalite), pyroxenes (ortho- and clino-, "OPX" and "CPX" in the jargon), feldspars (Ca-, Na- and K- bearing ; anorthite, albite and orthoclase), silica (quartz), pyrite (iron sulphide), metallic iron (with nickel) and something hydrous, so let's say a mica. That's 11 minerals. Something else needed for the round dozen.

But then it starts to get complicated. In around half of Earth's (or Venus') volume, the olivine would be unstable compared to a mineral called ringwoodite (which could soak up most of the water fraction in the mica - easily 0.25 % by mass (Earth is about 0.1% water by mass) ; but Mars, given the same proportion of elements would have almost no ringwoodite becasue it's too small. Mercury is smaller. I'm sure Hazen knows this (I think his institution measured the water-absorption of ringwoodite at lower-mantle conditions, if not himself personally). Which is why we'd really need Hazen's actual list of "*ur*-minerals".

Is that species count "low" for an early solar system? I don't think so, IF (big **IF**) we're talking about the mantle/ upper core chemistry. Those minerals, with their various solid solutions between end members and minor substitutions (e.g. titanium substituting for iron in the sulphide and pyroxene phases) will cover ... 95% plus of the atoms in the planet. Maybe 99%.

**BUT** if he's talking about the near surface, where the water gathers, temperatures are low, and potentially life can form (I know Hazen has drifted from the One True Path of Mantle Petrology into biology in the last decades), then yes, you get into literally thousands of "clay" minerals alone. Whole families of amphiboles also competing to get their atoms wet. Dozens of micas (I was thinking of biotite, probably the most thermally stable of the family) ...

> Wouldn't it be prudent to explore the idea that Earth was might already have had more complex molecules in the "soup" than just the twelve "ur minerals?"

Sounds like you're thinking about the biological end of things. Wet end certainly. So yes, the minerals would be much more complex at the surface. Poke them barely 100km below the surface (my mantle Petrology lecturer used to refer to anything within 100km of the surface as " *crustal ephemera* ; nowhere near equilibrium, and safe to ignore. Except for it's confining pressure - that's useful.") and they'll revert to those dozen-ish minerals I listed. It might take a hundred million years or so (1/45th of the age of any of the planets), but they'd revert to a mixture of those minerals with all the haste of a rock reading a thermodynamic equilibrium equation.

But near the surface, you can ignore all those minerals on my list, and just replace the whole lot with some generic "octahedral" and "tetrahedral" sheets from phyllosilicates (micas, the whole motley crew of clay mineral families) without caring that much about the labile (easily altered) cations and hydroxyl ions scattered around the sheet edges and between the sheet overlaps. Lots of interesting stuff there - I saw Alan Cairns-Smith lecture on his "Origin Of Life via clay minerals" book tour when I was an undergraduate. But the details of the mineralogy don't matter much - and I say that with "Mineralogy" in my BSc title, and a course unit in Soil Science where the *right* species of clays are really significant.

Does Hazen discuss this "*ur* mineral" concept online anywhere? I've brought his books in the past, and don't feel strongly inclined to do it again. Published papers are better value for money.


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