Meteorite Glossary - Letter P

Pallasite:

A class of meteorites characterized by a mixture of large olivine crystals in a matrix of nickel iron.

Petrology:

The study of the nature of minerals in rocks, or the minerals which are found in meteorites

Plessite:

A fine grained mixture of taenite and kamacite that often forms triangular fields bordering the taenite and kamacite crystals of octahedrite meteorites. But it is not a mineral itself instead it is made of the other two nickel iron minerals.

Polymorph:

A mineral with the same chemical composition of another but often with a different density and hardness. Often polymorphs in meteorites are formed by high pressure and high temperature. Diamond and graphite are common polymorphs of carbon.

Pyroxene:

A magnesium-iron silicate mineral family but distinct from olivine found in many different forms in meteorites.