| 0 | ICE (Hydrogen Oxide) |
| 0 | IDOCRASE (alternate name of Vesuvianite) |
| 0 | IGNEOUS (rocks that solidified from magma) |
| ILVAITE (Calcium Iron Silicate Hydroxide) | |
| ILMENITE (Iron Titanium Oxide) | |
| INDICOLITE (blue variety of Elbaite tourmaline) | |
| INESITE (Hydrated Calcium Manganese Silicate Hydroxide) | |
| IOLITE (variety of Cordierite) | |
| IRON (Fe) |