This is an irregular verb and the conjugations need to be memorized. A short lesson explains how. Mentir - French Verb Conjugations Learn how to conjugate mentir, an irregular -ir French verb. This is not an easy verb to conjugate, so you will need a good lesson to show you how.
Metamorphism occurs because some minerals are stable only under certain conditions of pressure and temperature. When pressure and temperature change, chemical reactions occur to cause the minerals in the rock to change to an assemblage that is stable at the new pressure and temperature conditions.
The presence of some specific minerals in a metamorphic rock can indicate the degree of heat and pressure it sustained. Metamorphic rocks are sedimentary or igneous rocks that have been modified or changed in form, that is, the size, shape and arrangement of the minerals in rocks, by heat or pressure. As they are derived from previously existing igneous, sedimentary or even metamorphic rock, their appearance varies from one to the other.