Minerals are naturally occurring substances that have a definite chemical composition. Minerals can be identified based on their physical properties such as colour, density, hardness and chemical property such as solubility. Energy sources come in many forms, including nuclear, fossil fuels like natural gas, oil and coal and renewable resources like wind and solar. Non-conventional Resources: of energy are renewable. Solar energy, wind energy, tidal energy, etc. are non-conventional sources of energy. Conventional Resources: are those that have been in everyday use for a long time. Firewood and fossil fuels are two primary conventional energy sources.