Quartz begins as a raw material quarried from the earth, but this purely raw quartz is not what you will be seeing on your countertop surfaces. Added to quartz before installation are binding agents, resins, and sometimes coloring materials to give the quartz a desired pigmentation or look as well as the sturdiness it is well known for. Quartz is not as susceptible to etching as quartzite. A quartz counter may withstand chipping and denting better than quartzite due to the flexibility afforded by the additional resins and binding agents.
Quartz is also able to withstand significantly high temperatures, which is beneficial in kitchen counter use, and it will not sustain damage even when exposed to heat up to 300 degrees Fahrenheit. However, temperatures above 300 degrees Fahrenheit may damage the resins in a quartz counter.
There is wider color variation available in quartz due to the coloring agents that can be added.