All of the Detect X spells (in addition to Message) have the following text in their description

The spell can penetrate barriers, but 1 foot of stone, 1 inch of common metal, a thin sheet of lead, or 3 feet of wood or dirt blocks it.

In this context, what does RAW have in mind for "Common Metal"? Are there any other classes of metal defined anywhere?

  • \$\begingroup\$ Are you actually looking for what is considered "fine metal" or just for what isn't considered "common metal"? I could imagine a super-thick ultra-dense wall of compacted nether-iron (something I just made up on the spot), which I wouldn't define as common metal, but wouldn't define as fine, either. \$\endgroup\$ May 29, 2013 at 23:54
  • \$\begingroup\$ Basically I wanted to know if there were "classes of metal" defined anywhere. \$\endgroup\$ May 30, 2013 at 0:01
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    \$\begingroup\$ I've edited your post to reflect that, since it's more to the point. Plus, whether there are "fine" metals is immaterial: what if there are classes of metal, but "fine" isn't one of them? You'd get a "no there isn't" instead of learning about what you really wanted to find - the theoretical metal classes table which "fine" is not on. :) \$\endgroup\$ May 30, 2013 at 0:17

2 Answers 2


As others have already noted, there's no RAW that I know of that define the idea of common metals beyond the statements in the spell descriptions. Since we're talking about detection, and possible deterrents to detection, it seems logical to me that the "commonality" of said metals is more intended to define the scope of the detection powers, rather than a purely scientific mechanism based on density or other qualities. So I'd address this as a function of game balance between magic and world economics.

In other words, common metals are whatever metals are commonly (and therefore, perhaps cheaply?) available in your setting. This would mean that walls or containers that resist scrying/detection would either be bulky (due to the required thickness of the "commonly" available materials) or very expensive (since presumably thin sheets of lead or more exotic metals would be harder to acquire). I would also extend the comment about lead to apply to other "non"-common metals.

For instance, I wouldn't classify precious metals such as gold or silver as "common" for these purposes, despite the fact that we "see" a lot of it in fantasy settings, because 1) their very value is predicated on their rarity, and 2) using them to line walls or containers is a fairly costly proposition, which I believe is in keeping with the intent of the detection spells text.

Likewise, anything that is widely used for weapons, tools, household goods, or construction, such as brass, iron, tin, pewter and copper would be common for the purposes of the spells.

And of course, anything exotic, such as mithral, adamantine, meteoric iron, etc. would be un-"common", as well as pricey/hard to work with.

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    \$\begingroup\$ Hmm, you're not thinking about what the wording implies. Uncommon metals aren't mentioned, which means they wouldn't block detect spells at all. Is that really what you'd want? \$\endgroup\$
    – starwed
    May 30, 2013 at 16:40
  • \$\begingroup\$ I think this answer completely misses the point of the quote. It's not about rarity or value, it's about what blocks the magic. It's an allusion, I think, to the lead bibs you wear when getting an x-ray: dense metal blocks the ray. Apparently it works the same way with detect magic et al. \$\endgroup\$
    – KRyan
    May 30, 2013 at 20:12
  • \$\begingroup\$ You could certainly interpret unmentioned materials as providing no barrier. Since it would have been impossible to give an exhaustive list, and given the variety of materials listed and their varying compositions, it seems to me to indicate that anything can block detect spells, the question is just how much it takes. After that, it's all about balance and the economics of magic (and counter-magic) in your setting. \$\endgroup\$
    – Zimul8r
    May 31, 2013 at 12:29

It basically means “not lead (or similarly dense metal)” – which of course isn’t all that specific.

It’s safe to say that iron, steel, and mithral (typical equipment metals) fall in that category. Adamantine, I’m less sure. Bronze, copper, and brass are probably common as well. Gold is denser than lead so it probably fits in the same category as lead.

Ultimately, the rules are simplistic and don’t make any attempt to be exhaustive. It’s pretty much up to the DM.

  • \$\begingroup\$ by 25 seconds..cmon \$\endgroup\$
    – user4000
    May 29, 2013 at 23:58
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    \$\begingroup\$ Gold is about twice as dense as lead... or did D&D change something? \$\endgroup\$ May 30, 2013 at 15:09
  • \$\begingroup\$ @EugeneRyabtsev oh whoops. What I get for thinking of lead as "the dense one". Fixing. \$\endgroup\$
    – KRyan
    May 30, 2013 at 16:22
  • \$\begingroup\$ Mithral is a 'typical' metal in your world? I'd expect it to be more in the 'rare' category, myself. \$\endgroup\$
    – Jeff
    May 30, 2013 at 18:43
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    \$\begingroup\$ @Jeff "Common" in the line about what blocks magic does not seem to have much to do with rarity, but rather with exceptional density versus "typical" (whatever that means. ferrous?) metals, which if anything mithral is lighter than. \$\endgroup\$
    – KRyan
    May 30, 2013 at 20:11

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