Speaking of balance, one of the best examples for the harmonious - and necessary - balance between the two poles (yin and yang, male and female, high and low, giving and receiving, heaven and earth) are the two Archangels Metatron and Sandalphon. These Twin Flames (often called Twin Brothers but Sandalphon is actually the feminine aspect) are in charge of the highest chakra (the Stellar Gateway - Metatron) and the lowest chakra (the Earth Star - Sandalphon) in the human energy field. Sandalphon is known as the tallest angel because he bridges Heaven (spirit) and Earth (physicality).
In addition to the seven major chakras there are several important chakras located outside the physical body - therefore called the transpersonal chakras - which are important for your spiritual well-being and wholeness.
The Earth Star chakra is the grounding point we use when we earth our energies and is found about 50cm below our feet. It is our connection to Mother Earth and helps keep us firmly "planted" into physicality, which is where we are meant to be in our physical incarnations. Being properly grounded through the Earth Star helps to keep our subtle bodies anchored and aligned correctly. To ground yourself, connect with the earth. Use grounding stones such as hematite, black tourmaline or smoky quartz- if you are sitting or standing you can place the stones on the floor between your feet, if lying you'll find the point between and below the feet. You can also place the stones around you, or wear them as jewelry. Hematite is naturally magnetic, so it is often sold as bracelets.
The Stellar gateway chakra is found above the Soul Star, as high as you can reach above your head. Once activated it is our direct line to the Divine Source. The connection needs to work both ways, as a spiritual exchange between you and the Divine. It gives access to infinite energy. The best way to attain the open state of the Stellar Gateway is through daily meditative practice as this enables a detachment of the heart and mind from the personal. Using this chakra allows access to Divine wisdom and compassion. Selenite (known as the "Angel Stone") is helpful for clearing the Stellar Gateway.
Katrina Raphaell has been instrumental in bringing this information to our awareness. You can read her explanation of these points and of specific healing stones in her book The Crystalline Transmission.