Smoky quartz's spiritual meaning is centered on grounding, protection, and the transmutation of negative energy into positive energy. It is associated with the root chakra and is believed to provide a sense of stability, strength, and security while helping to release fear, stress, and other unwanted vibrations. Historically, it has been used as a talisman for protection against negative forces. 
Smoky quartz is associated with the zodiac signs of Capricorn, Scorpio, Sagittarius, and Virgo. It is particularly beneficial for these signs due to its grounding and protective properties, helping them to stay balanced, focused, and stable.