What is a particle (in the geological context)?

Question

When I look up the term "grain size" in wikipedia it says this: "Grain size refers to the physical dimensions of individual particles of rock or other solid". What does particle mean in this context?

Answer 1

A particle, in its most general definition, is simply a small object. See the etymology in the wiktionary reference below. In geology, a rock such as granite is composed of a mix of minerals, like quartz, feldspar, and mica, often in crystalline form. If this igneous rock cooled more slowly, these minerals had time to form larger crystals. When you look at the rock, you would see larger specks than in a rock which cooled more quickly. Grain size is a way to quantify this.