Common Examples:
* Sand: A mixture of minerals, primarily silicon dioxide.
* Plastic: A wide variety of synthetic polymers.
* Wood: Composed of cellulose and lignin, which are complex organic polymers.
* Metals: Most metals are insoluble in water, such as iron, copper, and gold.
* Oil: A mixture of hydrocarbons that are nonpolar and don't mix with water.
Less Common Examples:
* Diamond: A form of pure carbon.
* Glass: A mixture of silica, soda ash, and lime.
* Rubber: A natural or synthetic polymer.
* Clay: A type of soil composed of fine particles of minerals.
* Concrete: A composite material made from cement, sand, and aggregates.
It's important to note that some substances are *slightly* soluble in water, even if they are generally considered insoluble. "Insoluble" usually means that the substance dissolves to a negligible extent.
