Biotite Quartz Approximately 8.5mm, Inner diameter approximately 16cm Biotite Quartz is a rare type of quartz that contains black, granular or needle-like inclusions of biotite (black mica). The contrast between the black inclusions and the clear quartz is beautiful, and it displays various expressions depending on the light. It is a rare natural stone with limited distribution. It is said to have effects such as mental stability, improved self-confidence, enhanced action, and improved intuition. It is also known as the "stone of life" and "amulet," and is believed to purify anxiety and negative thoughts, giving the power to move forward into the future. ■ Please be sure to read the profile. ・We plan to ship via regular mail. There is no compensation for shipping troubles, so we will accept changes to Mercari mail for +¥100. We cannot accept changes to the shipping method after purchase. ・We strive for prompt and courteous service. We look forward to connecting with people who can have serious and pleasant transactions (*^^*)