Specific gravity is the ratio of the density of a substance to the density of water. The specific gravity of clay varies depending on the type of clay and its mineral composition. Generally, the specific gravity of clay ranges from 2.5 to 2.8. Some specific examples include:

- Kaolin clay: 2.6

- Montmorillonite clay: 2.7

- Bentonite clay: 2.8

These values represent the average specific gravities of these clay types and may vary slightly based on the specific sample and its composition.