* Dominant Mineral: Olivine is the most abundant mineral in peridotites, often making up over 50% of the rock.
* Defining Feature: The presence of olivine is a key characteristic that differentiates ultramafic rocks from other rock types.
* Formation: Peridotites and other ultramafic rocks are formed deep within the Earth's mantle, where olivine is a primary constituent.
* Geological Importance: Olivine's abundance and unique properties make it a vital indicator of the Earth's composition, processes, and history.
In summary: Olivine is not just important, it's fundamental to understanding peridotites and other ultramafic rocks.
