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I am building a world where a rogue moon (or rogue planet or other larger celestial body) partially crashes into the main planet; the the residual shards would then form a smaller moon which becomes trapped in orbit around the planet. This is similarly to the giant impact hypothesis, which is one potential explanation to how our own moon may have been formed.

The celestial body which crashed in to the planet contains dust/soil similar to that of the dust on our moon, which has exotic properties (exact properties is irrelevant) and is highly useful for magical purposes. In the giant impact hypothesis for the formation of our moon, there are inconsistencies when it comes to the material composition - there are both similarities and differences between the material on the moon and on Earth. E.g., the iron oxide (FeO) content is very different but the oxygen isotopic ratios are essentially the same. So this means that there might have been some partial/imperfect exchange of material, but there are no solid evidence for it.

Would it be possible for such collision to transfer material from the moon to the planet it crashed in to?

Follow up questions:

Are there any evidence that moon dust have been incorporated into the Earth regolith (i.e., are there any evidence of such transfer in our world)?

Which properties of the moon dust would be required if I want it to have the ability to form crystals/solid rock over time?

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    $\begingroup$ I think this could possibly be an interesting question. don't delete it. Maybe try and refine the question to asking a more specific question on the topic. As I understand it Regolith is an all encompassing word for 'soil and bedrock' so maybe focus on if/how your story would identify the regolith as ancient 'alien' rock. you can also try a focussed question on Astronomy to point you in the right direction about what sort of minerals you are looking for and then come back and either ask another question or refine your current one about possible 'alien' rock types that may exist... $\endgroup$ – EveryBitHelps Feb 22 '17 at 21:08
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    $\begingroup$ ... I know the Chicxulub crater (the one they think formed after the dinosaur killer) has gravitational anomalies but how would a renaissance society figure that out? with the larger Theia impact that formed the moon, the evidence would be a lot harder to find. the Wikipedia summary suggests that the only physical evidence we have to support this is isotopic differences measured between earth and moon rocks. $\endgroup$ – EveryBitHelps Feb 22 '17 at 21:08
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    $\begingroup$ Regolith is just the dirt covering bedrock; most of terrestrial Earth is covered by it. I think what you mean is lunar soil, which is the regolith of Earth's Moon. That substance would be hard to come by on an Earth-like planet, what with its atmosphere/wind and water constantly mucking up the pristine mechanically-ground stuff of the Moon. $\endgroup$ – Azuaron Feb 22 '17 at 21:39
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    $\begingroup$ There is a lot information on the ~2 Billion year old Vrederfort Crater. Any fine sediment/dust/'alien rock' that survived the re-entry into the atmosphere and the shock of impacting the planet will have been deposited into the distorted geological layers. These will then have further eroded and redeposited over the following 2 billion years. so yes, alien origin of some rock minerals is a possibility. you just need to figure out how much will have survived and how much is close enough to the surface to make an 'impact' on the surface en.wikipedia.org/wiki/Vredefort_crater $\endgroup$ – EveryBitHelps Feb 22 '17 at 21:42
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    $\begingroup$ @Benjamin I made a suggested edit, which rewrites most of the question into what I believe would be on topic (but no guarantees) but still follow (how I understood) your question. It has just been sent to the review queue and may not be approved (so it might not be changed). If it gets approved, then please check it if you like the changes - if I misunderstood your question and changed it too much, then please feel free to edit it. Then try to send it to the reopen queue again. $\endgroup$ – Mrkvička Feb 23 '17 at 14:15
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In the impact, the rogue moon that hit the planet will cause a big scar. I am going to assume that such impact was caused eons before (intelligent) life wad formed on the planet. With enough time, the scar itself will heal and not leave any easily noticeable imprints of the event.

It will, for sure, deposit any loose matter that is on the surface of the planet. We're talking snooker on a celestial scale and even if the rogue moon/planet escapes, anything that is loose will be hurled forward by the momentum at the impact. Furthermore, with the impact both the planet and the celestial body will have large pieces torn off and while most of the pieces will be forming the new moon of the planet, some of them ought to fall down on it, too. I have not found any solid evidence that this is actually the case for our planet and moon, but some matter is inevitably transferred; exactly how much is, however, hard to tell. Even if a majority of the stones and dust misses the planet, some of it is bound to be captured by the gravity and it is bound to come falling down sooner or later.

If this is anywhere near how our moon may have formed, then it happened so long ago that the transferred magical rocks are deeply buried under ground. Although with the continental drift and other large scale events, pieces will finds it way to the surface.

You ask how they might agglomerate into crystals or rocks. An simplified explanation of the difference is that rocks are agglomerates of crystalgrains, meaning that small pieces of crystals are densely packed together while crystal are highly ordered molecular formations. A very common way to form rocks is by sedimentation, where looser material is packed densely by pressure from other matter which is deposited on top; if the dust and rocks from the moon are not able to form pure crystals, then this would be the most likely way that they eventually will make it into large pieces. In order for it form crystals, then it is required that the atoms it is composed of can form fairly periodic structures (although there are such things as quasicrystals, in which the atoms are ordered but not periodic). As author, you are of course free to choose whichever material you want as your lunar dust, it does not have to be the same as our lunar dust. As you used the word regolith - regolith is a term for any younger matter which has not yet formed sediments, it includes soil, gravel and other small pieces. If the rocks and dust from the moon is incorporated into the planet regolith at the time of impact, then that regolith can subsequently be packed into sedimentary rock and, thus, form larger rocks.

In short:
Yes, matter can very well be transferred from such event. Even if no matter were to be transferred, then there is still a possibility for rocks of the moon to make it down on the planet. Each day there are meteorites striking both Earth and the moon. Those hitting Earth are relatively harmless as our atmosphere protects us; for the moon, on the other hand, they have a chance to knock off pieces, which will be hurled into space. Such pieces will be orbiting Earth and the sun and will, eventually, fall down as lunar meteorites.

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    $\begingroup$ That original piece I did needed some rewriting - take this as a lesson, kids: don't drink and answer questions on WB.SE $\endgroup$ – Mrkvička Feb 24 '17 at 7:44
  • $\begingroup$ 1/2Excellent info (drinking errors included!). Yes, in my story, the impact happened eons before life evolved. My goal with this is to use this material as the "magical" source, or source of "power" that I can use in my story to make things happen like a steampunkish type world where its medival but with some advancments. $\endgroup$ – Benjamin Feb 24 '17 at 19:42
  • $\begingroup$ 2/2However, my main reason for asking is because I'd like this resource to still be tied to the Rogue Moon, as in the resource draws on the moon in the sky and pulls power from it to power my magic and my "wizard" for lack of a better term. It is also an explanation for a vampireish type of person in my story. An explanation for why when the moon is out, he is more powerful and has magic, etc. I will be writing in that the material is located in a specific place in the world because of this impact so long ago. $\endgroup$ – Benjamin Feb 24 '17 at 19:42
  • $\begingroup$ @Benjamin I'm glad I could be of help. I think it's an interesting idea for explaining magical powers. I would guess that the area where the impact occurred will be the one with the most deposited rocks, although this is such large scale event that there ought to be pieces scattered all over the planet to a certain degree. And even if most stones are buried, there are always ways for them to make it to the surface and found; land shifts and moves and eventually buried soil comes near the surface - and then there are always mines and caves where one can reach buried treasures more easily... $\endgroup$ – Mrkvička Feb 24 '17 at 20:20
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    $\begingroup$ @Benjamin There is, as far as I know, no easy way to message a person directly. Most commonly one creates a chat room and then post a comment with the link where the other person can see it. If you know that a person is frequenting a certain chatroom, then you can tag their name (@Name) in that chat room to notify them that you want to talk, but just writing to them in chat will not send them any notification if they are not there. Also, if ppl tag one-another too often in comments, then the system will spawn a chat link to make them go there instead. $\endgroup$ – Mrkvička Feb 24 '17 at 21:15
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Material is definitely transferred but the big question is: How much damage was done? If the damage was high enough, the material could be buried too deep to be meaningful unless you use it to explain a magical underdark.

A more likely way of transferring material that would be both close to the surface and not distributed too thinly to be useful would be is a celestial body were to break up do to gravitational stresses and some pieces of it were to fall to the planet. Another reason for a break up is that maybe the planet had a moon that the celestial object hit. That would offer moon rock plus whatever was in the other rock.

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