if the red mountain explode, in my thought the glass armor is made from the glass that miners would pick in the red mountain yes ok, so if morrowind almost everyone fleed from there how can we craft glass im not saying that we cant but at least , shouldn′t the dunmers selling glass for insane mounts of money in my kinda way i think is the dunmer would get someone to rule them (i dont know if they have or not) i think they could just rebuild Morrowind again.

of course im talking from the fourth Era

I can't think of a readily apparent lore reason. So I'd chalk it up to a design decision. The TESO videos suggest that thinks "touch stones" are important in developer thought. So I reckon they think that glass armor has to be in every game to make it an ES game. I'd rather see the logic that lead to glass armor in every game but now I'm discussing my own speculations.

Glass was not only in Morrowind, it can be found (rarely) in Skyrim as well.

http://www.uesp.net/wiki/Lore:Malachite

Also, I had trouble reading your OP but I hope I answered your question.

Not to mention, Glass Armour is actually an Altmer creation.

So Raw Glass/Malachite is probably found in every province (except Cyrodiil, who don't have any Glass/Malachite mines).

I'd be most interested in why some armors carry over and others don't. Why did they choose the armors they to preserve from Morrowind to Oblivion? How about from Oblivion to Skyrim? What is different about Mithril or Chitin that doesn't warrant a second appearance?

if i had to guess its because chitlin was a dunmer design, made with local bugs, it would be very rare in cyrodill. As for mithril...well i think it was too...lotr, i mean it came right out of the books, and they wanted to make their own shiz

Chitin armour... Falmer armour?
Not sure about mithril though, completely forgot about it til you brought it up there.

Glass armor is made from volcanic material. Red Mountain is just the most famous volcano on Tamriel. There is plainly volcanic activity in the eastern reaches of Skyrim, so we know there are other sources of the materials.

I have a feeling there may be at least one or two. They do tend to change a jungle into a forest shrink the game space when compared to the lore. Games just can't handle Jungles the size of the provinces.

It'd be nice to see the occasional peice of chitin or bonemold or trollbone floating around skyrim's eastern half. *hint to modders*

Chainmail's gone too, although mostly because it's already part of most armor that there's no need to make it a separate set of armor.

Mithril, I've always thought was some sort of ayleid/elven exclusive armor. At least in Oblivion, it features the bird/feather/Auriel motifs that the Ayleids had on everything.

The Manual of Armor also states that Mithril, Elven, and Glass are fairly rare in the Empire. Elven became more readily available when the secrets of its crafting were leaked out of the Summerset Isles, and Glass became more available as glass mining increased in Morrowind and Skyrim, and possibly elsewhere.

Whatever happened to Adamantine?

Trollbone was Nordic, actually, and I was a little surprised not to find any. I always feel like those troll skulls littering Skyrim are taunting me...