When substances do not mix thoroughly and evenly (like sand and gravel), the mixture is said to be heterogeneous
Both substances could be seen
When solid materials are mixed with solid materials, each of the mixed materials can be easily identified from one another.
Sand is a crystalline quartz that (if clean) Homogeneous.
answer:Sand ang Gravel is HETEROGENOUSExplanation:When substances do not mix thoroughly and evenly (like sand and gravel), the mixture is said to be heterogeneous. A heterogeneous mixture consists of visibly different substances. Another example of a mixture is salt dissolved in water.
Explanation: gravel only refers to the size of a rock
Sand ang gravel is a heterogenous mixture