The rocks that give the most reliable radiometric dates are those that have undergone a single, well-defined geological event. This means that the rocks must not have been disturbed or altered since they were formed, and that they must not contain any younger material that could contaminate the sample.

The best rocks for radiometric dating are:

* Igneous rocks: These are formed when magma or lava cools and solidifies. The crystals in igneous rocks grow as the magma cools, and they can trap radioactive isotopes from the surrounding environment.

* Metamorphic rocks: These are formed when existing rocks are changed by heat and pressure. The minerals in metamorphic rocks can recrystallize, and they can also trap radioactive isotopes from the surrounding environment.

* Sedimentary rocks: These are formed when sediments, such as sand, mud, and gravel, are deposited and compressed. The minerals in sedimentary rocks can trap radioactive isotopes from the surrounding environment, but they are more susceptible to alteration and contamination than igneous and metamorphic rocks.

The type of rock that is most suitable for radiometric dating will depend on the specific circumstances. For example, if the goal is to date a volcanic eruption, then igneous rocks would be the best choice. If the goal is to date a mountain-building event, then metamorphic rocks would be the best choice. And if the goal is to date a sedimentary deposit, then sedimentary rocks would be the best choice.

By choosing the right type of rock, and by using careful sampling and analysis techniques, radiometric dating can provide accurate and precise ages for geological events.