Kāmākhyā — the menstruating goddess of Nilachal Hill
Kāmākhyā of Nilachal Hill, Guwahati, is the most famous of the 51 Shakti Pīṭhas — said to be where the yoni (womb) of Sati fell. There is NO anthropomorphic image in the sanctum, only a natural cleft rock moistened by an underground spring. The annual Ambubachi Mela (June) marks the 3-day "menstruation" of the goddess, when the spring runs red with iron oxide; the sanctum closes and reopens on the 4th day. Over a million pilgrims converge annually. Assam's Shakta traditions, including tantric bhairavī pūjā and animal sacrifice (still practiced), are most intensely practiced here.
Daily aarati at dawn and dusk; abhisheka with water/milk/turmeric; kumkum offering; red hibiscus; oil lamp. For Tantric or non-Brahmin shrines: goat-sacrifice (traditional; increasingly symbolic pumpkin-breaking).
Hinduism's goddess-traditions are vast and diverse — 51 Shakti Pīṭhas, 10 Mahāvidyās, 9 Navadurga, 8 Ashta Matrika, hundreds of regional forms. Each is a distinct face of the one supreme Mahā-Devī.