Tabasheer (Hindustani: तबाशीर or طباشیر) or Banslochan (बंसलोचन, بنسلوچن), also spelt as Tabachir or Tabashir, is a translucent white substance, composed mainly of silica and water with traces of lime and potash, obtained from the nodal joints of some species of bamboo.^[1] It is part of the pharmacology of the traditional Ayurvedic and Unani systems of medicine of the Indian subcontinent.^[2] It is also an ingredient in many traditional Iranian^[3] and traditional Chinese medicines.^[4]

Tabasheer is claimed to provide a variety of health benefits. It is variously regarded as an antipyretic, antispasmodic, antiparalytic, restorative and aphrodisiac.^[5]

Tabasheer that has a blueish tint (usually called neel or neelkanth) is considered superior to tabasheer that has the "more plain" yellow or white color.^[6]

Not all bamboo stems contain tabasheer. Likely candidates are found by shaking bamboo stems, which can make the mineralized tabasheer inside produce a rattling sound. These stems are split open to extract the tabasheer.^[6][7]

Although a part of the ancient Ayurvedic system of medicine, it has been postulated that the use of tabasheer originated in the Adivasi aboriginal tribes of India.^[1] Tabasheer was extensively exported from India for thousands of years, including through Arab traders during the medieval period.^[1] The town of Thane, close to the west coast of India, was famous as a clearing center for tabasheer in the twelfth century CE.^[8] It was called σάκχαρον in the writings of Pedanius Dioscorides, a Greek pharmacologist who practiced in Rome in the time of Nero.^[5]

Tabasheer is referred to as Tvaksheera (त्वक्षीर) in Sanskrit, which means bark milk.^[5][9] Other Sanskrit-derived names have been applied to tabasheer as well, including bamboo sugar (vans-sharkar), bamboo camphor (vans karpoor) and bamboo manna.^[8] It is called Tian Zhu Huang in Mandarin, which means "heavenly bamboo yellow."^[4]