Antimineral shell

Antimineral shell was an abjuration spell that created a barrier of force that prevented all manner of elemental creatures and animated elements from entering the zone of effect.

Effects
The area protected by this spell was a 10 ft (3 m) radius hemisphere centered on the caster. The effect lasted over two hours at a minimum (longer for higher level casters). The invisible force field generated by this spell was impervious to animated stone and metals (such as armor or weapons), stone-based lifeforms such as galeb duhr, xorn, and xaren, golems and similar constructs, and creatures from the Elemental Plane of Earth. As an added bonus, it also prevented entrance of other creatures of elemental origin such as aerial servants, djinns, mephits, and salamanders for example.

Antimineral shell did not prevent entry of normal, non-animated stone or metal such as a thrown boulder or a rockslide. If the caster attempted to push the shell up against a warded creature in order to get it to move, the spell was soon broken.

Components
In addition to verbal and somatic components, this spell required a drop of an acidic compound, such as the caustic acid of a black dragon.