To derive is defined as to come from, be created from or be developed out of something else. An example of derive is when you get the idea for a new fund raising event based on the event the previous year.
Rubidium: geological information. Rubidium is far too reactive to be found as the free metal in nature. It is relatively rare, although it is the 16th most abundant element in the earth's crust. Rubidium is present in some minerals found in North America, South Africa, Russia, and Canada. It is found in some potassium minerals (lepidolites, biotites, feldspar, carnallite), sometimes with caesium as well.
Rubidium oxide is the chemical compound with the formula Rb 2 O. Rubidium oxide is highly reactive towards water, and therefore it would not be expected to occur naturally. The rubidium content in minerals is often calculated and quoted in terms of Rb 2 O. In reality, the rubidium is typically present as a component of (actually, an impurity in) silicate or aluminosilicate. A major source of rubidium is lepidolite, KLi 2 Al(Al,Si) 3 O 10 (F,OH) 2, wherein Rb sometimes replaces K. Rb 2 O is a yellow colored solid.