srdiamondThis isn't unusual. Iridium is basically synonymous with tipping material; a hard metal alloy welded to the tip to keep the nib's tip from wearing down from use. As I understand it, fountain pen nibs are generally tipped but not dip pen nibs which are disposable.
Goulet has a very informativevideo on it:
srdiamond@sakamichi is correct. That said, iridium is a bit of a misnomer. Iridium itself is incredibly rare and an arse to weld to anything. Most fountain pens use an alloy of iridium, osmium and a platinum group element (platinum or ruthenium usually) for easier workability.
srdiamondNo, only for how long the nib lasts you. Like @diserasta said, "iridium" isn't really used in modern pens and most use a similar type of alloy. From Richard Binder's site: "Although “iridium” is a common term for the tipping material, modern tipping materials rarely contain the actual element iridium; the most common element used is ruthenium, with admixture of such other metals as platinum."
I don't think you're ever going to notice a difference between a nib tipped with one mixture over another when writing.
srdiamondI think part of the issue is that Levenger is not a dedicated pen company. They do manufacture their own branded pens, and resell many others, but they also sell many other types of "lifestyle" products. Their target market Is not, I don't think, heavily experienced fountain pen enthusiasts. For one thing, their most expensive branded fountain pen (the True Writer Select, at $159), does not come with a gold nib, but rather a steel one. Point being, maybe they're trying to use "iridium point" as a marketing gimmick to less experienced users. Just a theory. Btw, I have a Select and it's an excellent pen. I also very much like the TW Classic offered in this drop.
srdiamondWith the exception of stub nibs just about all steel nibs have an iridium point. That's the ball at the top of the nib where the pen touches the paper. It is formed from rare, hard metals, not always iridium. Without that tip the pen would be scratchy.