Material

Most items in Adom are made from following materials:

cloth, leather, stone, iron, mithril, adamantium, eternium, gold, glass, "various", crystal.

Only metalic [iron, mithril, adamnatium, eternium] stuff can be smithed. Items made of gold appear on smithing list but golden ingits do not exist.

Material affect few things

Weight - if version of same thing exists material influences the weight of item.

Elemental resistance - higher metals [mithril, adamantium, eternium] and crystal made items are resistant to fire and acid, while most other are not. Notable exception are stuff granting elemental resitance, they are immune to corresponding elemental despite material used - so fire resistance ring [made from wood] is unaffected by fire and iron made bracers of resistance are immune to fire and acid.

Artifacts are undestructable by elemental attacks despite material made from [ankh is made from gold].

Iron made stuff is the only one that rusts in water [rivers, underwater, slipping in poools, dipping in regular uncursed water potions] or can be rusted by rust monsters. From ToEF tests iron is also somewhat fire resistant - last longer than leather/wood made material but melts eventually.

Corrosion - some monsters have ability to corrode weapons upon being hit. This mostly affects iron made weaponry, while mithril and adamantium are somwaht resistant. The only materials immune to corrosion are eternium, stone and crystal. [Attacking with something like leather armour still needs investigation].

There is such thing as wooden weapons [simple clubs, simple quarterstaves and pick axes]. These are vulnerable to corrosion, not affected by rust, do not appear as smithable stuff [so can not be fixed via forge] although are affected by weapon scrolls normally, they also are vulnerable to acid and fire [later gives message of weapon burning away opposed to melting away for metalic one]. That is rather realistic behavior of wood. Question why Creator made pick axe wooden is another topic...