# Do gems dissolve in acid?



## ThomasBJJ (Oct 11, 2002)

Pardon my ignorance on gems and acid in the real world, but would a black dragon be able to store gems in a vat of acid without said gems dissolving?

If it matters, the gems are rubys and diamonds.

Are there any metals that are immune to acid (sttel, bronze, gold)? Certain kinds of stone? Would clay pottery be able to contain acid?


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## Crothian (Oct 11, 2002)

Depends on the acid.  Gems are basically pretty rocks, and some acids will eat through rock, some don't.


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## Emongnome (Oct 11, 2002)

Diamonds (I think) are immune to acids.  Other gems I'm not sure about, but, as Crothian said, it is very dependent on the type of acid, as well as the concentration.  There are some Fe/Ni alloys immune to sulfuric acid (at certain concentrations and temps), but hydrochloric eats those same alloys for lunch.  All in all, D&D is not meant for any details in this area, as a house rule, I would say metals are affected by acids, gems are not.  Keep it simple, if possible.  Corrosion is a science onto itself, and I don't know of any charts that include gems off the top of my head.


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## Fade (Oct 11, 2002)

Most gems, like glass, are resistant to most acids. Any metal but gold will dissolve very quickly, and gold will dissolve in a mixture of concentrates hydrochloric and nitric acid.

Pottery, if well made in a 'porcelain' fashion and not just earthenware, should work. Glass is resistant to all but hydrofluoric acid, although strong alkali can effect it.


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## Tarek (Oct 11, 2002)

*Gems and Acids*

It also depends on the kind of gem. Opals (and crysopals, jelly opals, and other hydrated gemstones) would be particularily vulnerable, as would Jade and Amber.

Diamonds, being pure carbon in a tightly bonded octahedral crystalline matrix, are not chemically reactive to most acids.

Tarek


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## Mahali (Oct 11, 2002)

*Re: Gems and Acids*



			
				Tarek said:
			
		

> *
> Diamonds, being pure carbon in a tightly bonded octahedral crystalline matrix, are not chemically reactive to most acids.
> 
> Tarek *




True, but they sure look pretty when they burn.


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## Alchemist (Oct 11, 2002)

I like the bit about how diamond is thermodynamically less stable than graphite, so that diamond ring you bought your wife is slowly turning into a pencil.  They don't mention that on the "Diamonds are forever" commercials. 

Granted, it is a painfully slow process.  But still.


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## Stalker0 (Oct 11, 2002)

now the big question is... in a billion years what will we use for wedding rings?


But anyway, I would go with most gems are immune to normal acids. Just be consistant with it, I don't think your players will find that beyond belief.


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## Tyrrell (Oct 11, 2002)

*Re: Gems and Acids*



			
				Tarek said:
			
		

> *
> Diamonds, being pure carbon in a tightly bonded octahedral crystalline matrix, are not chemically reactive to most acids.
> 
> Tarek *




Nitpick dimonds are isometric not octahedral.

Sorry, I've had too much mineralogy.  I can't really control it anymore.

Edit;  unless you meant that the carbons are sitting in octahedral sites.  I guess in that case you couild describe the "matrix" as octahedral.   I just thought matrix = crystal system/ unit cell as a knee jerk reaction.

See I told you that I couldn't control it.


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## Al (Oct 11, 2002)

Although this may be completely wrong, I would assume that if the acid originates from the black dragon it would be hydrochloric.  The green dragon's breath weapon is chlorine, and I'm assuming that it is not too different.  However, I cannot be sure as the descriptive texts are not detailed enough to give clear indicators (obviously not chemists).

Given that it is hydrochloric, quite a few gems should be able to survive, and the rubies and diamonds will probably be okay.  If in doubt, just say that do.  Hopefully your players won't know/care any different.  If they make sounds otherwise, just don't give them treasure at all.  That usually stops the pedantic whingers  .


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## Celebrim (Oct 11, 2002)

This is one of those questions that depends alot on whether you are using fantasy acid or realistic acid.  

Fantasy acid has one attribute - potency.  The more potent it is, the more things it disolves and the more material it disolves relative to its volume.  Fantasy acids can disolve objects having several times there own volume.  Fantasy objects resist all acids equally.  Either the acid resistance is high enough to resist the acid, or it is not.

Realism is much more complex.  Probably too complex.

Let's suppose Al is right, and Black Dragons produce hydrocholoric acid or at least its equivalent (which is weird, because Chlorine is not an element; where is the Elemental Plane of Chlorine?)

Some gems will do alot better than others.

Diamond is fairly impervious to acids of all sorts.  However, it can be made to burn in the presence of certain oxidizing agents.

Corundum and most of the other aluminum gems (like Alexandrite and I think Garnet) are essentially impervious to acids.  

After that, it gets complicated.  Peridot will disolve almost instantly in hydrocloric acid. Topaz on the other hand is unaffected by hydrocloric acid, but will be disolved by nitric adic. Hydrofluoric acid will disolve opals, aquamarines, and amethyst.


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## Alejandro (Oct 11, 2002)

Why not use the object hardness rules? Stone has a hardness of 8, so the dragon can store them in 1d6 acids without fear.


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## radferth (Oct 11, 2002)

Who knew there were so many closet chemists here.  Remember that in the game context, and chemical attack is treated as acid, so things like a green dragon's chlorine breath and basic substances like lye do "acid" damage.  When I am running (and my players can testify I use an irritating amount of real world science at times) I use the following rules.

1) In game "acids" are assumed to be run-of-mill acids or bases unless otherwise specified (e.g. no HF).

2) Gold, platinum, glass, ceramics, and hard gems (diamonds, rubies, saphires, etc) are assumed to have huge amounts of acid resistance (virtual immunity).

3) Silver and copper are fairly acid resistant, but not immune.

4) Assume an alchemist of enough skill could divise a solvent that inflict "acid" damge on just about anything, or even one that is selective (e.g. metal but not wood or flesh, stone or flesh but not metal, etc.)

To answer the original inquiry, yes, I'm sure a black dragon could drool out acid the right strength to harm characters and the equipment, but not diamonds and rubies.


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## Number47 (Oct 11, 2002)

That would be up to 1d8 without harm. You can and certainly should rule that diamonds have a higher hardness. I'm not sure if rubies should have a higher hardness than stone, but you could say 10 without getting too much argument from most people.

According to the rules, acid does full damage to objects, yes? I don't have the rulebooks in front of me. I know that fire only does half...


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## Alejandro (Oct 11, 2002)

Oops, acid does half damage to objects. So, rinsing gemstones in a vat of 2d8 acid is just fine.


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## Number47 (Oct 11, 2002)

...or more if you up their hardness to more than 8...


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## Kibo (Oct 11, 2002)

Number47 said:
			
		

> *That would be up to 1d8 without harm. You can and certainly should rule that diamonds have a higher hardness. I'm not sure if rubies should have a higher hardness than stone, but you could say 10 without getting too much argument from most people.
> *




Considering the etymology of adaminite/tine/antium diamond should have the hardness of whichever one of those your campaign uses.


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## Alchemist (Oct 11, 2002)

Celebrim said:
			
		

> *
> Let's suppose Al is right, and Black Dragons produce hydrocholoric acid or at least its equivalent (which is weird, because Chlorine is not an element; where is the Elemental Plane of Chlorine?)
> *




Being a not-so closet Chemist, I can tell you with great degrees of certainty that we consider Chlorine to be an element.  It's number 17 on your periodic table. 

I would just KISS and say gems are impervious to such things.


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## Al (Oct 12, 2002)

Alchemist, I assume that Celebrim was referring to Chlorine not being an Element (as in, no Chlorine Elementals) rather than an elemen (i.e. chemical element).  Although annoyingly enough, there are no acid elementals either.

Back on the main topic, the issue of acid damage vs. hardness is fine if you use a 'fantasy acid' model.  Using a 'realistic acid' model, it is more difficult.  All acids have a 'maximum' strength (usually around 17M), so if the gemstone won't dissolve in that, it won't dissolve in any form of (that particular) acid, no matter what the damage.  Conversely, gemstones subject to reaction with certain acids will usually go if the damage is significantly less.  The damage itself could be explained by quantity of acid in combination with molarity (strength), so a 100 point breath weapon could simply be twice as much volume as a 50 point breath weapon without actually being 'stronger'.  Unfortunately, this flies in the face of 'acid resistance'- which, if working in real chemical terms, can resist 1 litre of acid pretty much as well as 10 litres, assuming they are the same strength.

Given that this is 'fantasy' though, and given the parameters implicit in acid resistance, it's probably just easier to use the damage/hardness routine.  DnD is a game, not a chemistry lesson.


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