How much biotite is a sample of gabbro likely contain?

A sample of gabbro typically contains a small amount of biotite, often ranging from 0% to about 5% by volume. Gabbro is primarily composed of plagioclase feldspar and pyroxene, with biotite being a minor accessory mineral. The exact amount can vary depending on the specific geological conditions and the composition of the magma from which the gabbro formed. In some cases, biotite may be more abundant, but it generally remains a subordinate component.