The Sacral Chakra
The Sacral chakra is the socialisation chakra. It governs the endocrine system, the auto-immune system, female reproductive organs, the digestive process and, most importantly, our ability to "sit" into life.
Its natural colour is orange, though generally peach tones work better to rectify a damaged chakra. When this chakra is functioning badly (an almost habitual process for 20th/21st Century humans) it will produce a wide variety of ailments and symptoms - poor digestion, ulcers, low resistance to infection, inability to combat viruses, tiredness, irritability, shyness, hormonal imbalances, menstrual problems, reproductive problems, alienation - the list goes on and on.
Since one of the major functions of this centre is to convert the raw instinctual physical power of the base chakra into energy which can be brought under the logical reasoning power of the Solar Plexus, when the Sacral is blocked it gives rise to rage and violence without reason nor morals. You can probably see where many of society's current problems are arising from.
The Sacral chakra is located in the lower belly, two or three inches below the naval. It is sometimes known as the splenic chakra.