The source is from the fossil of the skeleton of ancient large mammals, such as deer, oxen and elephant types. The medicinal material is mainly produced in the areas of Shanxi, Inner Mongolia Autonomous Region, Gansu, and Hebei, etc., collected all year round and stored in the dry place. It is broken into pieces when it is used and the crude or calcined one is used.

Medicinal Properties: Sweet and pungent in flavor, slightly cold in nature and attributive to the heart and liver meridians.

Actions: Tranquilize the mind, calm the liver and suppress the hyperactive yang, astringe and invigorate the kidney to preserve essence.

Application  
1. It is used for restlessness, epilepsy and insanity. For restlessness, palpitation, insomnia, poor memory and frequent dreams, it can be combined with Zhusha ( Cinnabaris ) , Yuanzhi ( Radix Polygalae ) and Suanzaoren (Semen Ziziphi Spinosae), etc.; for epilepsy, convulsion and insanity, it is usually combined with Niuhuang ( Calculus Boris ), Dannanxing ( Arisaema cure Bile ) and others that can resolve phlegm and arrest spasm.
2. For irritability and dizziness caused by deficiency of yin leading to hyperactivity of yang, it is usually combined with Muli ( Concha Ostreae ), Baishaoyao ( Radix Paeoniae Alba ) and Daizheshi ( Haematitum ), etc., such as Zhengan Xifeng Tang (Decoction).
3. It is used for syndromes of slippery prolapse. For kidney-deficiency syndrome manifested as emission and spermatorrhea, it is used every time with Mull (Concha Ostreae), Shayuanzi ( Semen Astragali Complanati ), and Qianshi ( Semen Euryales), etc., such as Jinsuo Gujing Wan (Pill); for all kinds of clear leukorrhagia and menorrhagia, combined with Muli (Concha Ostreae), Haipiaoxiao (Os Sepiellae Seu Sepia) and Shanyao ( Rhizoma Dioscoreae ); for spontaneous perspiration due to superficial asthenia and night sweat due to yin-deficiency, usually combined with Muli ( Concha Ostreae), Fuxiaomai ( Fructus Tritici Levis ) and Wuweizi ( Fructus Schisandrae ) , etc..

Besides, the Duanlonggu (Os Draconis Usta) that is ground into powder has the action of sucking up moisture and treating skin ulcer disease, so it can be used externally for exudative prurigo and unhealed pyocutaneous disease after evacuation of pus.

Usage and Dosage:
15 - 30 g is used in decotion for oral use, which is broken and then decocted earlier. Just right amount is for external use. The calcined one is used for astringing and invigorating the kidney to preserve essence and the crude one is used for other syndromes.