I put together these tables below to provide a more detailed view of disenchanting results in Cataclysm Classic.
Item Rarity and Type
The type and quantity of materials produced from disenchanting can vary by item type (armor or weapon), item level, and rarity. The following general rules can be used:
| Dust | uncommon armor (75%) and uncommon weapons (20%) |
| Essences | uncommon armor (20%) and uncommon weapons (75%) |
| Shards | rare equipment (100%), epic equipment below level 50 (100%), and rarely from uncommon equipment (3-5%). |
| Crystals | high-level epic equipment (100%) and extremely rarely from rare equipment (~0.5%) |
WoW Classic
Skill |
Level Req. |
Dust |
Essence |
Shard / Crystal |
| 1 | 5-10 | 1-2x  Strange Dust |
1-2x  Lesser Magic Essence |
- |
| 1 | 11-15 | 2-3x Strange Dust |
1-2x  Greater Magic Essence |
 Small Glimmering Shard |
| 25 | 16-20 | 4-6x Strange Dust |
1-2x  Lesser Astral Essence |
Small Glimmering Shard |
| 50 | 21-25 | 1-2x  Soul Dust |
1-2x  Greater Astral Essence |
 Large Glimmering Shard |
| 75 | 26-30 | 2-5x Soul Dust |
1-2x  Lesser Mystic Essence |
 Small Glowing Shard |
| 100 | 31-35 | 1-2x  Vision Dust |
1-2x  Greater Mystic Essence |
 Large Glowing Shard |
| 125 | 36-40 | 2-5x Vision Dust |
1-2x  Lesser Nether Essence |
 Small Radiant Shard |
| 150 | 41-45 | 1-2x  Dream Dust |
1-2x  Greater Nether Essence |
 Large Radiant Shard |
| 175 | 46-50 | 2-5x Dream Dust |
1-2x  Lesser Eternal Essence |
 Small Brilliant Shard |
| 200 | 51-55 | 1-2x  Illusion Dust |
1-2x  Greater Eternal Essence |
 Large Brilliant Shard Nexus Crystal
|
| 225 | 55-60 ** | 2-5x Illusion Dust |
1-3x Greater Eternal Essence |
Large Brilliant ShardNexus Crystal
|
** Items in the 57-60 level range from the Burning Crusade expansion will disenchant into Burning Crusade materials. These items have 80+ item level listed under the required level. Regular Classic greens stop at 65 item level.
Burning Crusade (Outland)
Skill |
Level Req. |
Dust |
Essence |
Shard / Crystal |
| 225 | 57-63 | 1-3x  Arcane Dust |
1-3x  Lesser Planar Essence |
 Small Prismatic Shard |
| 275 | 64-70 ** | 2-5x Arcane Dust |
1-2x  Greater Planar Essence |
 Large Prismatic Shard Void Crystal
|
** Items in the 67-70 level range from the Wrath of the Lich King expansion will disenchant into WotLK materials. These items have 130+ item level listed under the required level. Regular TBC greens stop at 120 item level.
Wrath of the Lich King (Northrend)
Some level 73 items have lower item level, so they will disenchant into lower-tier materials from the 67-72 range.
Skill |
Level Req. |
Dust |
Essence |
Shard / Crystal |
| 325 | 67-72 | 2-3x  Infinite Dust |
1-2x  Lesser Cosmic Essence |
 Small Dream Shard |
| 350 | 73-80 | 4-7x Infinite Dust |
1-2x  Greater Cosmic Essence |
 Dream Shard Abyss Crystal
|
Cataclysm Classic
It's harder to tell just based on the required level what each item disenchant into in Cataclysm, so the item level listed here is the white "Item Level" text listed under the required level to equip.
Skill |
Item Level |
Dust |
Essence |
Shard / Crystal |
| 425 | 272-305 | 2-3x  Hypnotic Dust |
1-2x  Lesser Celestial Essence |
 Small Heavenly Shard |
| 450 | 305+ | 2-5x Hypnotic Dust |
1-2x  Greater Celestial Essence |
 Heavenly Shard Maelstrom Crystal
|