Are There Any Mineralogists in the Audience?



It’s pathetic is what it is.






Thanks in advance, my darlings!


  1. sithrazer says

    I started in with a reply, then I realized I lacked a real good definition for ‘minerals’ and that my questions and point were on things you are probably currently trying to work out and I’d just be trying my hand at mind reading.

    I restarted along a different line of thought, then came to realize that was much better suited to metallurgy and stock markets.

    Now I’ve had the epiphany that I am up way, way too late (early?) and should really just go to bed before I hurt myself.

    As I now feel obligated to do, time to dream Broken Dreams:

    • sithrazer says

      I apologize for the embedding, I don’t even know how it did that.

      …too late, apparently I just hurt myself. >.<

  2. says

    Hi Dana,
    Wikipedia has the standard geologic definition:

    So, a mineral is a naturally occurring inorganic solid with a characteristic structure and composition.

    From a more pragmatic point of view, when ionic solids form (with cations and anions attracting each other and repelling themselves), the most energetically favorable geometric positions for them to bind each other is generally not random, and any non-random co-ordination at the atomic scale will have a large degree of repetition and symmetry at the micro to macro scales. That repetitive pattern is called the crystal structure, and is one of the characteristics of most minerals.

    The simplest difference between minerals on the surface of the earth and minerals in space is that most earth surface minerals (unless recently brought up from the deep by volcanoes, tectonics, or rapid erosion) are relatively stable in the presence of water, and many minerals are altered or deposited by water.

    In space, this is not the case, as there isn’t much water around.

    Because water enables a host of complicated and interesting and varied sorts of reactions, planets like Earth have much more diverse mineralogy than dry planets. This makes Earth much more attractive places to mine.

    Bug me (Chuck Magee) on google + is you want details, weird speculative mineralogies, or mcguffins that aren’t *too* implausible.

  3. says

    We really don’t know much about asteroids. I have often wondered if there might be “terrestrial minerals” on some of them… that comprise the debris of a planetary collision such as the one that formed our moon.

  4. chris evo says

    If you want a detailed overview I recommend picking up a book like “Rock Forming Minerals” by Deer, Howie and Zussman. A lot of geologists I know swear by their DHZ. It’s not exactly organized to answer your questions, though.

    It’s not the best IMO but it’s what got popular around where I live. Any book of that type will make a handy reference.

  5. Ashley Moore says

    Not a full answer, but a pointer for looking:
    The universitality of physics means that there is nothing that could form on Earth that couldn’t potentially form elsewhere, given similar conditions.

    The conditions that make Earth differ from asteroids, thus causing difference in mineral forming would be:
    1. Water cycle. This means that minerals that form in the presence of water would be less common. (Although, I believe that some asteroids are found to have water on them). Also, sedimentation can only occur with a water cycle, so asteroids can not have things like sandstone, limestone or marble.
    2. Pressure. Earth is much larger than any asteroid, so pressure forming minerals would not be the same.
    3. Magnetosphere. An asteroid would not have magnetically aligned minerals.

  6. Ashley Moore says

    On the other hand, Unobtainium is much more prevalent on asteroids. For reasons not fully understood, but thought to be related to the Plot Cycle.

  7. Graham says

    I am not a geologist, but no-one has yet mentioned that the Earth has life on it. Here are some possibilities:

    I vote for Zhemchuzhnikovite. I would guess too that the fact that life has oxygenated the atmosphere makes a difference (iron oxides?).

    Another difference the atmosphere makes is that the surface of asteroids is exposed to cosmic rays, which I think makes some isotopes that are very rare on Earth.

    Also, Helium-3:

  8. Dana Hunter says

    You guys are amazing. Keep it coming! Apologies for not replying personally right now – I was up until nearly sunrise, which means I slept late, and now work beckons argh – but I’ll do so by late tonight.

    I adore you all!

    (ps. If your comment gets briefly stuck in moderation, it’s just because I have the spam battler dealie set to flag anything with more than two links. Don’t let that discourage you! I’ll have intermittent access to ye olde blog throughout the day, so I’ll rescue you. Link to as much yummy stuff as you like!)

  9. Reginald Selkirk says

    Robert Hazen is the go-to guy for questions like this. Read this to pick up some key terms, then search on those for more:

    Mineral Evolution

    The mineralogy of terrestrial planets and moons evolves as a consequence of selective physical, chemical and biological processes. In a stellar nebula prior to planetary accretion, unaltered chondritic material with approximately 60 different refractory minerals represents the starting point of mineral evolution. Subsequent aqueous and thermal alteration of chondrites, asteroidal accretion and differentiation, and the consequent formation of achondrites results in a mineralogical repertoire limited to the approximately 250 minerals now found in unweathered lunar and meteorite samples…

    You get the drift. There are a lot more minerals on Earth than existed in the primordial whatzit, some of that due to tectonics, and some to the presence of life. Probably the best-known factor is that our present atmosphere has a lot of oxygen (~ 20%) which is due to biological processes like photosynthesis.

  10. Reginald Selkirk says

    And maybe you’ve heard mention of iridium. It is not common on Planet Dirt, and is less rare in asteroids. Thus the presence of an iridium layer is considered a marker for meteorite impact sites.

    Imagine the proto-solar system functions like a giant centrifuge, and separates the lighter from the heavier elements (think uranium enrichment). Then you could have different elements being prevalent in different zones.

  11. lockwooddewitt says

    Quartzville. We need to get you to it. But only during warmer months.

    There’s no way to give a tidy little thumbnail overview of mineralogy, even a smaller subdivision like mining/economic mineralogy. Some more focused questions and info would allow more focused answers. Some return Q’s: what material is being mined? What is the broader geological context? What is the climate/ecology of the area? Should we assume the planet is essentially earth-like? Smaller or larger? The answers to these & other aspects of the situation would all influence to the types of minerals likely/unlikely to be present.

    Here’s a puzzle for you; when you think it through and figure out the answer you’ll have some insight into why I can’t provide much in the way of clear information so far.

    Mars turns out to have much more lithic diversity than we could have guessed even 10-15 years ago. Despite this, I’d be willing to wager a fair sum that blueschist & banded iron formation will not be found on that planet, because I doubt they exist there. Why not? What other earth rocks and minerals are unlikely to exist on Mars?

  12. F says

    Something I haven’t seen mentioned yet, which you can consider as an appended point 4 to Ashley Moore’s list: Earth entirely melted itself, so there is a certain differentiation of layers that wouldn’t occur in a body not large or solid enough to do that. Which is why Earth’s crust (and most all of the Moon) are aluminum and silica-rich, and why Earth has a large iron core (and hence, a decent magnetic field).

    Minerals found only in space: look at the chondrites. Only small bodies that undergo no melting will look like the piles of stellar nebula grains that they are. Carbonaceous chondrites are rarer and a bit more interesting. Iron-nickel bodies are (or were) large enough to melt, at least partially, at some point. Minerals like olivine and serpentinites (some of the coolest mantle minerals in Earth, IMHO) are found in asteroids, and metals are found in their reduced states (call them minerals or not) as grains or great lumps.

    If you were mining asteroids for metals, minerals, so to speak, are not directly important, unless you want to refer to a pure or mixed metal as a mineral.

    Planets lacking a large internal heat source like Earth are not going to have things like subduction, uplift, vulcanism, and all the minerals these things produce or expose. If it was hot enough for initial differentiation, but not to continue to be geologically active, the crust will be something like that of Mars or Venus. If there is no water for weathering or to become a chemical part of a mineral, (especially without any super-hot water), or a planet with no life, the crustal minerals are not going to look anything like Earth’s. A Planet-sized body without any of these things will be lacking iron deposits, gypsum, limestone, gold, diamonds, etc… Of course, you may not have a world with a lot of water if it has no large iron core (and no magnetoshpere) unless it is a colder world or the star doesn’t throw off much of a stellar wind.

    Hm. A world that is geologically dead, but has water and weather would be really odd. You’d have sedimentary rocks and clays with no organic components, and the world would be pretty flat if it is not extremely young.

    There isn’t going to be any free oxygen without life, so there are not going to be oxidized minerals and carbonates and such.

    I suppose if you were to start with a basic idea of what you want in a fictitious planet, you could start with some parameters, make sure they aren’t mutually exclusive, and build from there.

    You could chose to have an alien star system that had initially much higher (heavier) metal content, if you want. Say it condensed from a nebula that was seeded by one or more relatively near Type II supernovae.

  13. Jim Baerg says

    Check out this:

    Note that that the only elements worth mining in space to bring to earth rather than for use in space would be the siderophile elements, especially the platinum group.

    Siderophile means it tends to concentrate in metallic iron, so earth’s supply of the siderophile elements is concentrated in the core where it is rather hard to get at. About 4.5 Gy ago some some asteroids melted enough to separate into a rocky mantle & metallic core (see & for why)
    The asteroid cores would be much easier to reach than earth’s.

    IANAM but am a geophysicist & have thought about what (if any) McGuffinite could make space pay.

  14. Tamsin says

    Not a mineralogist here, just a third-year undergrad, but I can suggest a few things.
    A young Earth-like planet (less than about 2 billion years old) may have komatiites (ultramafic volcanic rocks) in far greater abundance than on present-day Earth, where they are rare and all known ones have undergone metamorphism since they were erupted in the Archean (mostly). Wikipedia has a decent article on komatiite which includes a brief section on its economic importance and some interesting links. Here’s one link you may find especially relevant.
    Carbonaceous chondrites are also pretty interesting – meteorites with calcium-aluminium-rich inclusions which also contain titanium, zirconium, hafnium and rare earth elements.
    There are some groups of elements that are depleted in the Earth’s crust relative to their overall abundances in the solar system. These may be more abundant on other bodies in the solar system and a lot of them are of significant economic importance: siderophile elements including gold, cobalt, iridium, manganese, platinum, palladium and various others; and chalcophile elements including silver, mercury, zinc, cadmium and bismuth. Wikipedia has more on these element classifications.

  15. justawriter says

    I’m thinking that an interesting take would be to look at the economics of the situation. Down on the earthlike planet, a large percentage of the cost of metal is the refining – separating the valuable metals from the oxygen, sulfur, carbonate and other anions that allow the metals to be concentrated by water. That’s what makes the metals so expensive, along with the rarity of heavier elements which, as others have pointed out, get concentrated at the center of the planet. OTOH, the asteroid miners have plenty of metal around, unoxidized, but they would need the light elements, namely water, air, carbon and salt to survive and increase their population.
    Then you have the differences in shipping charges. It’s easy to get something from space to the bottom of a gravity well. You drop it, ideally in a box that can survive the trip. But unless your story involves a “wantum mechanical” (derivation: Star Trek: what the director wantum, the writer delivered) means of space travel, all that stuff that is common to the point of being free on the planet (air, water, salt) is hideously expensive in space.
    Possible humorous aside: you could postulate that some common vegetable, say the potato, simply refuses to grow in microgravity. So a block of nickel large enough make a full stainless steel kitchen is worth the same as the extra large fries from McDonalds delivered to space.
    And to be more to the point of the question you actually asked, as well as expanding on Tamsin’s point, kimberlites, the volcanic rocks that are pretty much the only source of diamonds, are only found in rocks that are the age of the first continents. Putting your story on a much younger planet than earth means your heroes could watch volcanoes spew out diamonds. That sounds hella cool to me.

  16. Robert B. says

    Ashley Moore is quite right about the physics. On the other hand, since an alien planet just like Earth might be boring, here’s how physics might give you different minerals anyway:

    Every planet would have the same elements, but different worlds might have different amounts of each element, depending on their star. Stars have different amounts of “recycled material”; in other words, stars are partly made up of stuff that was previously a part of a different star. Since the heavier elements are created inside stars by fusion and other nuclear processes, recycled starstuff (having been through more fusion) has more metals and other heavy elements, and since planets are made from stuff emitted from their stars, the planets will follow suit.

    Stars near the center of galaxies, with lots of neighbors to borrow from, will have more recycled material and more heavy elements. Stars near the edge of galaxies will have less. And if certain elements are more or less common, I’m guessing that some minerals that are rarely seen on Earth would be much more prevalent. I don’t know minerals, but to those who do: what kind of things might you see if, say, the crust was 5% selenium? Or in the other direction, what if it was only 10% silicon?

    Interesting related facts:
    * By star standards, silicon is a heavy element. (Very roughly, silicon is the element that makes rocks rocky.) Stars with little recycled material would be less likely to have rocky planets at all; the planets you did get would be more apt to have miles-deep ocean over the whole surface, or to be too light to hold an atmosphere.
    * A lot of heavier elements are poisonous to Earth life, though presumably life that evolved on these “poisonous” worlds would have a higher tolerance.
    * Iron will be relatively common on any rocky world: it’s at a “dead end” in the element creation process, so it tends to pile up in stars and gets passed down to their planets. Light planets will have less iron than Earth does, of course, but still more iron than, say, cobalt or chromium.

  17. says

    Dana, I wrote a little about meteorites and mining for Accretionary Wedge #13 – along with links and things. Some elements, not minerals, to mine on asteroids:

    “These elements include gold and platinum, aluminum, magnesium, nickel, cobalt, platinum, and titanium, aluminium, gold, silver, zinc and other base and precious metals, and a whole host of resources depending on asteroid type:

    C, D, P: H2O, CO2, CH4
    B, G, F: nickel and iron
    Q, S, M: nickel, iron, silicates, and platinum group elements”

    Links in the post go to a couple other geoblogosphere posts on asteroids.” These are mostly elements. Silicates are minerals, but I don’t know what silicates would be found.

    For minerals on asteroids or extra-solar-system planets, I’d take up Lab Lemming’s offer and talk to @glacialtill.

    • Lyle says

      Let me suggest that you start with the minerals in Basalt. It is found on the moon, and also on Mars and recently Vesta. That means olivine pyroxene and plagiclase feldspar. Quartz to some extent, but the rhyolite/granitic suite would require a planet that recycles basalt thru continental type crust. You could invent things like the Stillwater complex in MT, if you want something to mine, or Sudbury On, which was at least partly caused by a meteor impact. Then look at what ores are found in basalts and you have a basis for on or off planet ideas (since Vesta was added to have Basalt)