Fine grained yellowish-beige stone (possibly phyllite).
 
The four-faced and eight-armed goddess resembles in many aspects the Buddhist goddess Usnisavijaya (Tib. gTsung tor rnam par rgyal ma). The principal difference is the presence of four heads instead of three. The goddess is seated in the diamond attitude (vajrapatyankasana) on a double pedestal with a double projection at the front (pancaratha). She is clad with a cloth tied around the waist with a belt. she wears jeweled ornaments, namely a five-pointed crown above each of the three faces, two pairs of circular earrings, necklaces with attached beaded strings and pendants, ornaments at upper arms, wrists, ankles and feet. She holds the following attributes in her eight hands:
            buddhasramana mudra                  fearlessness (abhaya mudra)
            visvavajra                                          bow (capa)
            arrow (sara)                                      stalk of a flower supporting...(?)
            gift bestowing (varada mudra)(?)  threatening (tarjani mudra)

Unisavijaya, the "victorious goddess of the usnisa", is a very popular deity in Tibetan Buddhism and is described in the Sadanamala (SM 191, 211.212).
Images of Unisavijaya are rare in Indian art, but the ritual of this goddess was popular in Tibetan Buddhism. This sculpture is the work of an Indian artist from North-Eastern India and possibly made for a Tibetan Buddhist monk.

Usnisavijaya
Usnisavijaya (Tibetan: gTsug-tor rNam-par rGyal-ma; English: victorious goddess of the usnisa) is a goddess of longevity in Buddhism. She wears an image of the Budda Vairocana in her headdress. She is the most popular Budda goddess in Nepal, Tibet, and Mongolia.

Chandra, Lokesh, 1979. "Iconography of the Goddess Usnisavijaya". JISOANS, Vol. X. Journal of the Indian Society of Oriental Art, New Series. Pp. 17-29, pl. VI, fig. 5 - References to the iconography of Usnisavijaya

Chandra, Lokesh, 1980. "Comparative Iconography of the Goddess Usnisavijaya". Acta orientalia Academiae Scientiarum Hungaricae. Acta orientalia Academiae Scientiarum Hungaricae. Pp. 125-37, i illus - References to the iconography of Usnisavijaya

de Mallmann, Marie-Thérèse, 1975. Introduction à l'iconographie du tântrisme bouddhique. Paris: Adrien Mainsonneuve (Jean Maisonneuve successeur (1970). Pp. 389-390 - References to the iconography of Usnisavijaya

Nath, Amarendra, 1977. "An image of Usnisavijaya from Khara Khoto: Identification", JISOANS, Vol. VIII. Journal of the Indian Society of Oriental Art, New Series. Vol. VIII. Pp. 41-47, pl. XVIII - References to the iconography of Usnisavijaya

Sèngué, Tcheuky, 2002. Petite Encyclopédie des Divinités et symboles du Bouddhisme Tibétain. Editions Claire Lumiere . Pp. 256-257 - Références françaises: Ushnishavijaya