A variety of keys are provided here, ranging from very simple ones that cover limited rocks, to complex ones that cover all the rocks dealt with at this site. The keys are listed blow in order of complexity.
Metamorphic Mineral Key - pdf versionMetamorphism produces some common, well known minerals, as well as ones only a geologist would recognize. It is possible to study and understand metamorphic rocks with knowing these minerals. But, each mineral typically has something important to say about the rock. Some metamorphic minerals are diagnostic of the rock they belong to, such as serpentine (rock serpentinite) and talc (rock soapstone). Other minerals are extremely useful for measuring the intensity of metamorphism, such as chlorite, biotite, garnet, staurolite, kyanite, and sillimanite. At other locations in this site we explore some of the minerals, but this key will allow you to identify the most distinctive metamorphic minerals.
A Very Simple Metamorphic Rock Classification - pdf versionThis key is the simplest possible. It concerns only the main eight types of rocks produced in Barrovian and contact metamorphism. This key is meant for the most basic introduction, such as at the elementary school level.
A Common Metamorphic Rock Classification - pdf versionThis key is the same as the one above, except that it adds serpentinite and soapstone.
The two keys below are comprehensive, covering all the major metamorphic rocks. They are split into two keys, one for granular and one for foliated rocks. Since not all specimens are clear cut, sometimes the same rock shows up on both keys, to cover all contingencies. The footnotes with each key tend to be important since they explain important exceptions.
Granular Metamorphic Rock Key - pdf Foliated Metamorphic Rock Key - pdf