Lava stone was used by American Indians when entering battle for its qualities of strength and clarity. It’s believed to provide strength (physical and mental) when facing difficult situations.

Hematite grounds and protects us. It strengthens our connection with the earth, making us feel safe and secure. It endows us with courage, strength, endurance and vitality. A "stone for the mind", Hematite stimulates concentration and focus, enhancing memory and original thought. Hematite utilises the magnetic qualities of our yin-yang energies to balance the meridians within the body and to provide a stable equilibrium between the ethereal nervous system and the physical nervous system. 
Chakras - Base Chakra 
Zodiac - Aries, Aquarius 
Element – Fire/Earth

Onyx is a stone recommended during times of pain and sorrow. It’s known for balancing male and female polarity and increasing hormonal balance. It’s also said to help with objectivity and making intelligent decisions. In addition, it’s believed to help strengthen one’s bones.
Black Onyx is associated with our Base Chakra.
Zodiac - Gemini, Leo 
Element - Earth

Black Crystal is associated with the solar plexus chakra, and known as an excellent ground stone. Many believe it aids in relieving stress and anxiety, while calming a hyperactive mind. Others associate the stone with detoxifying the digestive system, and protecting against radiation. 
Chakras - Base Chakra, Solar Plexus Chakra 
Zodiac - Scorpio, Capricorn 
Element - Earth/Air

Snowflake Obsidian is known for stabilizing and balancing the body. Snowflake Obsidian is believed to purify a negative atmosphere, and remove toxins from one’s body. It’s also believed to be an excellent stone for pain relief of arthritis, muscular aches and spasms. Removing shock and trauma that arises after injury, while improving circulation, are other qualities the stone is thought to provide.
Chakras - Base Chakra 
Zodiac - Scorpio, Sagittarius 
Element - Earth/Fire