Based on mineral composition:
* Igneous rocks: These rocks, formed from cooled magma or lava, can be very rigid and brittle, especially those with high silica content like granite and rhyolite.
* Metamorphic rocks: Some metamorphic rocks like quartzite and marble can also be very rigid and brittle depending on their composition and grain size.
Based on physical properties:
* Hard rock: This is a general term for rocks that are resistant to scratching and abrasion. Hard rocks are often brittle, but this isn't always the case.
* Brittle rock: This describes rocks that break easily under stress. This can be due to their mineral composition, grain size, or the presence of fractures.
Other terms:
* Fractured rock: Rocks with a network of cracks and fissures can be considered brittle, even if the original rock was not.
* Crystalline rock: Many crystalline rocks like quartz and feldspar are inherently rigid and brittle.
Ultimately, the specific name for a rigid brittle rock depends on the context and the particular rock type being discussed.
