It’s not. This is the actual text:

“No state shall…make anything but gold and silver coin a tender in payment of debts;”

It says that the only money that states can create are gold and silver coins.

You’re probably thinking Article 1 Section 8 and this clause:

“To coin money, regulate the value thereof, and of foreign coin, and fix the standard of weights and measures;”

Which, again, is not in violation because value doesn’t mean what it trades for but what the coin is physically made up of. The definition of Dollar is a hard-set weight of pure silver, which Congress can then say what the alloy must be made up of. Congress can’t alter the weight of pure silver present in the alloy nor can Congress dictate what that coin will trade for.

What this means is that all Congress can do is say that the 371.25 grains of pure silver that make up the definition of a Dollar (that number is to Dollar as 12 is to Dozen. You can’t just redefine a unit of measurement like what is being passed off as a Dollar today is) must be present in a coin and given other metals to alloy with it, so when someone accepts a coin with $1 on it, they know it contains 371.25 grains of pure silver no matter what bank or state issued the coin. It makes it so money can cross state lines and be privately issued, severing political control over coins. See http://mises.org/daily/4149 for more details.

What is passed off as currency today is actually Unconstitutional as the Constitution does not give Congress power to issue paper scrip as coining currency specifically relates to metals, not paper. Congress also was never granted power to give a single entity monopoly control over currency, meaning the Federal Reserve Bank is also Unconstitutional on top of issuing unbacked paper currency. Further, even if the Federal Government does decide to issue copper, nickel, or iron coinage, it cannot use the term Dollar because, as noted above, Dollar is a very specific term for a specific weight of pure silver. Since Congress was given no power to price-fix, attempting to call copper, nickel, steel, brass, or even gold $1 would also violate the granted powers of the Federal government. Yes, I said it, gold CANNOT be defined as $1 under any circumstance as the purchase price of gold in terms of silver is never constant. It may be used as currency, but the coin must be stamped with it’s weight. So a penny cannot be stamped as 1 cent because 1 cent is 3.7125 grains of silver, not 2.4375 grams zinc and 0.0625 grams copper. All that coin can be stamped with is 2.4375 grams zinc and 0.0625 grams copper to denote what it is made of. Uncle Sam is breaking the rules by using Federal Reserve Notes and forcing us to use it (no Constitutional Articles give government of any level power to force people to use chosen money).