Somewhat related to this question, now that we've established how useless gold is as anything (wow I was such an idiot), what about crystals? For instance, something like the diamond armor from Minecraft.

What if there were a humanoid, mobile, solid lump of crystal - how tough would it be? Would you be able to shatter it with a simple blow from a steel sword? Or would it be completely impervious to harm? Would it matter what kind of crystal it was, i.e. would diamond be tougher than emeralds?

Edit: thanks for all the suggestions in the comments! I think I may have used the word 'crystal' wrongly. I meant something more like precious stones - i.e. Sapphires, rubies, quartz etc. Also, I'm kind of imagining them pre-processed, and not as ores.

Edit #2: Don't think of it as a layer of armor - imagine if it were a solid lump all the way through. These things are completely animated by handwavium.

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    $\begingroup$ That really depends on the crystal, the properties of crystals vary by a huge amount. You might need to be more specific to get a good answer. $\endgroup$
    – Tim B
    Commented Feb 8, 2015 at 17:09
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    $\begingroup$ All of my golems are made out of adamantium. It really helps with those pesky pigeons. $\endgroup$ Commented Feb 8, 2015 at 17:22
  • $\begingroup$ I would also suggest looking at the types of steel historically used in weapons. It may be very informative for you! $\endgroup$
    – PipperChip
    Commented Feb 8, 2015 at 18:24
  • $\begingroup$ Pretty much all the gold you'll ever come into contact with in your entire life will be in the form of crystals. Likewise for many other inorganic materials including practically all metals. (Types of crystals.) $\endgroup$ Commented Feb 8, 2015 at 20:22
  • $\begingroup$ If your machines or golems or whatever are completely animated by handwavium, why don't you make them completely out of unobtanium? $\endgroup$
    – KSmarts
    Commented Feb 9, 2015 at 19:18

2 Answers 2


As Tim B mentions, its all about the choice of crystal. It's also a question of how perfect you try to structure your crystal.

Hydroxylapatite is a good example. It scores a 5 on Mohs scale of hardness, which is pretty reasonable (quartz rates a 7). However, it is very brittle, fracturing quite easily when subjected to unexpected loads. On its own, it would fail miserably as armor.

On the other hand, build a matrix of proteins like amelogenins and enamelins and bathe the whole structure in a calcium iron rich liquid, and you have the hardest component of the human body: the enamel of our teeth. The proteins hold the hydroxylapatite together after it fractures until it can be repaired with the calcium in our saliva.

If you instead choose to intersperse your hydroxylapatite crystals with chitosan, you have the material of choice of the Peacock Mantis Shrimp for its clubbing appendages. The hardness and resilience of this composite material is so extraordinary that mantis shrimps in captivity have been known to shatter the glass aquariums they are kept in. They even outdo modern synthetics for hardness and durability by such a margin that we're trying to learn from it in the world of engineering!

  • $\begingroup$ Moral of the story: metamaterials rock! $\endgroup$
    – Cort Ammon
    Commented Feb 8, 2015 at 18:19
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    $\begingroup$ It should be noted that Mantis Shrimp's clubs are non-uniform in their structure. That is, the stuff that ought to be hard is, whereas other parts get softer as needed. Those little clubs are really a marvel. $\endgroup$
    – PipperChip
    Commented Feb 8, 2015 at 18:23
  • $\begingroup$ That... Mantis thing... is pretty danged cool. $\endgroup$ Commented Feb 9, 2015 at 1:13
  • $\begingroup$ Aren't you describing composite materials instead of metamaterials? $\endgroup$
    – March Ho
    Commented Feb 9, 2015 at 12:55
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    $\begingroup$ @MarchHo I had to look up the definitions, but I believe you are right. I was going from the definition that the properties of metamaterials depend on their structure more than their bulk properties, but apparently that was only part of the definition. I think, at some point, I wanted to give structures like teeth a little more credit than we give carbon fiber and epoxy resin structures, so I may have unconciously given them a promotion =) $\endgroup$
    – Cort Ammon
    Commented Feb 9, 2015 at 15:55

It is hard to scratch a diamond because of it's hardness but it will break if the blow is strong enough because it has a low toughness compared to steel. If you hit with a mace , you will crack the armour. Depending on the thickness of the armour and the weight of the sword it might be possible to break the armour. But the mace is much more useful.

The problem is that diamond is poor to absorb or redistribute the energy of the impact.For gold, it was the opposite: almost impossible to break but too soft.

The ideal combination would be a mix of the two. One softer material to absorb the impact in order to protect the harder layer. Alone, they are useless. Together... I would not recommend it. It would cost a lot. If a human would be to wear that armour, you would just need to push them over or walk at a safe distance. Your better with another combination of material.

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    $\begingroup$ But man, you could go to an afterparty for rap singers and walk in like you own the place! $\endgroup$
    – Cort Ammon
    Commented Feb 8, 2015 at 18:07
  • $\begingroup$ Would you damage your mace if you smacked a solid lump of diamond with it? $\endgroup$ Commented Feb 9, 2015 at 1:14
  • $\begingroup$ @FeaurieVladskovitz : It depend on the strength of the impact. It might deform it. $\endgroup$
    – Vincent
    Commented Feb 9, 2015 at 2:15
  • $\begingroup$ And this is why we have things like steel... (or alloys in general) $\endgroup$
    – kutschkem
    Commented Feb 9, 2015 at 10:34

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