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Minerals that make up rocks can be broken down into a few basic elements, The most common ones,  Silicon, Aluminum, Iron, Hydrogen and the compounds are limitless. Sands are not a pure element, even though it is largely Silicon etc.. In a small scoop of soil you can likely find over half of all elements on Earth, including Gold and Radioactive elements, but in very tiny quanties.

Some of the elements bond togeather and form minerals. What minerals they form depends on what elements are available and conditions  they form (like temperature and pressure) Both Diamounds and graphite, pencil lead, are minerals, that contain only carbon, but the carbon bonds in different patterns, Quartz, talc (talcum powder) and gold are other minerals. There are over 4,000 different minerals. Any minerals bond togeather and form rocks. like minerals the type of Rock that forms depends on available minerals and conditions.