The pink or white feldspar crystals in granite, for example, are compounds of potassium. In turn, when feldspar weathers to clay, the potassium becomes part of the clay particles that make up the world's soils. Sodium does not occur innature as a metal because it is so reactive. For example, sodium will react violently with water as this description shows. A silvery pellet of sodium.
Sodium corrodes quickly in airand so has few uses.
A sodium pellet is dropped onto water in a small dish. A chemical indicator has been added to the water, partly to show the trail of the sodium as it moves across the water, and also to show what happens as the sodium reacts. The indicator is colourless unless the solution becomes alkaline, in which case it turns bright pink. The heat released causes the metal to form a rolling molten ball. Notice that the water has turned bright pink.