There are non-crystalline and crystalline forms of silicon dioxide. The most common type of crystalline silica is quartz (CAS 14808-60-7).
Different types of rock and rock products can contain different amounts of crystalline silica, for example:
| Type | Amount of crystalline silica (%) |
| Marble: | up to 7% |
| Limestone: | up to 2% |
| Granite: | Variable, between 25% to 50% |
| Natural sandstone: | Variable, between 52% to 95% |
| Engineered stone** | Up to 97% |
| Aggregates, mortar and concrete: | variable, between 20% to 98% |
*The composition of natural stones, such as limestone, granite and sandstone, can vary significantly depending on the source. These values are typical ranges and should be used as general guidance only. Always verify the specifications of the exact material you are working with, consult the supplier, or conduct your own testing.
** Subject to certain exceptions, the importation, supply, processing, and installation of engineered stone benchtops, panels and slabs is prohibited in Australia.