Materials

The material of an item determines whether an item is burnable or soluble. It also affects armour skills and the effects of allergy intrinsics.

About Materials

Solubility

Whether or not an item will dissolve in acid is decided by its material--however, it is worth noting that if any item (such as a Ring or artifact) grants Acid Resistance, the item is automatically insoluble.

Flammability

Like solubility (above), whether or not an item will burn when exposed to fire is also decided by its material. Similarly, items which would normally burn but grant Fire Resistance do not burn.

Skills

Several of the Armour skills in the game grant a bonus if a worn piece of Armour is of an appropriate type. These skills are listed in a material's description. Note that Wood is also covered by Leather Armour, and paper by Cloth Armour. Iron Armour is pretty obvious, and Exotic Armour covers items made of mithril or silver, as well as (impromptu shields of) gold, glass, flesh, or stone.

Note that no non-shield piece of armor is useful as an impromptu shield, specifically so that you can't use, e.g., a set of Plate Mail as a super-shield! However, while most non-armour items have no AC of their own, if you are holding a book or other item in your off-hand, you can get the extra AC point for a matching material skill.

Allergies and Vulnerabilities

Some monsters in the game are allergic to certain materials. Currently, silver and gold are the only materials that any monster can be allergic to. A creature that is allergic to a material takes extra damage from attacks with a weapon made from that material, and takes damage while wearing or wielding an item of that material. No monster is naturally Allergic to Gold, but most can be temporarily made so, by a Gold Beetle. Monsters allergic to silver are listed under "silver", below. The avatar can become temporarily Vulnerable to Silver, by eating the corpses of these monsters!

Edibility

While the only material that can be eaten by most creatures is flesh, some monsters can eat (sometimes only) items of certain other material types. They are listed under the material type.

Material Types

Cloth

Items: Plain Robe, Floppy Hat, Pointed Slippers.
Armour Skill: Cloth Armour.
Cloth is dissolved by acid, but (oddly) not burnable.

Paper

Items: most books, and all scrolls. The books not made of paper are the Bloody (flesh), Leather, Runed Leather, Glass, and Gold books.
Armour Skill: Cloth Armour
Paper is dissolved by acid, and burnable

Wood

Items: Wooden Shield, Kite Shield, all Staves, Arrows and Flaming Arrows, Club, Torch, Bow, Wooden Ring, Clogs, and several wands: Wooden, Curved, Forked, Jeweled, Twisted, Purple, and Gem Encrusted.
Armour Skill: Leather Armour
Wood is dissolved by acid, and burnable

Leather

Items: Leather Cap, Sandals, several other Boots (Riding, Hiking, Winged), Leather Tunic, Studded Leather Tunic, the Leather and Runed Leather Books, and Studded Leather Gorget.
Armour Skill: Leather Armour
Leather is dissolved by acid, but not burnable

Iron

Items: Dagger, Spear, Rapier, Lightning Rapier, Knife, Short Sword, Long Sword, Flaming Sword, Mace, Ice Mace, Warhammer, Iron Helm, Buckler, Round Shield, Tower Shield, Banded Mail, Splint Mail, Chainmail, Plate Mail, Iron Shoes, Iron Torc, Iron Ring, Mobius Ring, Iron Wand, corpse of an Iron Golem.
Armour Skill: Iron Armour
Iron is dissolved by acid, but not burnable

Silver

Items: Silver Dagger, Silver Spear, Silver Sword, Mirror Shield, Silver Circlet, Silver Ring, Silver Wand.
Armour Skill: Exotic Armour
Silver is dissolved by acid, but not burnable. Monsters vulnerable to silver include: Lich, Ghost, Daemon, Ice Daemon, Baezl'bub.

Silver Attacks

Creatures vulnerable to silver will take additional damage when attacked with weapons (or items improvised as weapons) made of silver. For most such creatures the effect will be double damage; Ghosts only take regular damage, but they're otherwise immune to physical attacks. (And any elemental damage done by a silver weapon to a Ghost will be doubled.) This also applies to beam damage from wands made of silver! Silver weapons (and items used as improvised weapons) will occasionally dull if used against non-vulnerable targets. For each such attack, a silver item has a 1% chance of having 1 point subtracted from it's Enchantment. Artifacts are immune to this dulling effect, and wands don't dull from being fired.

Silver Equipment

Any item made of silver that is equipped by a an entity that is vulnerable to silver will do searing damage (2d3 per item) to that entity for each turn while the item is equipped. However, throwing a silver weapon (firing from the quiver or throwing from inventory) does not.

Gold

Items: Gold Wand, Gold Crown, Gold Book, Gold and Ruby Necklaces, Gold Beetle corpse, most rings (the non-obvious exceptions are: Mobius (iron), and Jade (stone)).
Armour Skill: Exotic Armour skill.
Gold is not dissolved by acid, and not burnable

Gold Attacks

Entities which are allergic to gold will take additional damage (usually double damage) when attacked with weapons (or items improvised as weapons) made of gold. Currently the game defines no "proper" weapons made of gold, so all gold "weapons" are improvised (except the Gold Beetle's bite), but this also applies to beam damage from wands made of gold! Gold items used as improvised weapons will occasionally dull if used against non-allergic targets. For each such attack, a gold item has a 10% chance of having 1 point subtracted from it's Enchantment. Artifacts are immune to this dulling effect, and wands don't dull from being fired..

Gold Equipment

Any item made of gold that is equipped by a an entity allergic to gold will inflict searing damage (2d3 per item) to that entity for each turn while the item is equipped. However, throwing a gold item (firing from the quiver or throwing from inventory) does not.

Mithril

Items: Mithril Chainmail
Armour Skill: Exotic Armour
Mithril is not dissolved by acid, and not burnable.

Glass

Items: all Potions, Crystal Platemail, Glass Book, Glass Ring, Glass Wand
Armour Skill: Exotic Armour.
Glass is not dissolved in acid, and not burnable

Stone

Items: Boulders, Rocks, Earth Hammer, certain corpses (Cave Troll, Stone Golem, Earth Elemental), Pearl Necklace, Stone Ring, Jade Ring, Stone Wand, Jade Wand
Armour Skill: Exotic Armour
Stone is not dissolved by acid, and not burnable. Items made of stone can be converted to flesh by the Stone to Flesh spell. Most such items will become Meatballs.

Flesh

Items: Food (except corpses marked as "inedible" and that of a Water Elemental), Bloody Book.
Armour Skill: Exotic Armour
Flesh items are dissolved by acid, but not burnable. They are also edible, though some have side-effects. Items made of flesh can be converted to stone by the Petrify spell. Most such items will become Rocks.

Aether

No usable items are made of Aether, though some monsters have "ethereal" bodies (these do not leave corpses, and also cannot be petrified).