spherulites
/ˈsfɛrəˌlaɪts/
noun
- Small, round, or spherical mineral structures that form inside rocks, often looking like tiny balls or spheres.
- Some spherulites form when lava cools very quickly, trapping gas bubbles that later fill with minerals.
- Under the microscope, the spherulites in the obsidian appeared as perfect little circles.
- The geologist showed us spherulites in the volcanic rock, each one no bigger than a pea.