The mountain weasel (Mustela altaica), also known as the pale weasel, Altai weasel or solongoi, is a species of weasel that prefer to live in environments that are usually high in altitude (11,480 ft (3,500 m) or more) as well as rocky tundra and grassy woodlands covered in green vegetation. They rest in rock crevices, tree trunks, and abandoned burrows of other animals or the animals they previously hunted. The home range size of this animal is currently unknown. Geographical distribution for this species lies in parts of Asia from Kazakhstan, Tibet, and the Himalayas through to Mongolia, northeastern China, southern Siberia, Korea, and also some parts of Russia. The most common area for this species, however, is Ladakh, India. The conservation status, according to the IUNC, is near threatened because it is considered to be in a significant decline and requires monitoring maining because of habitat and resource loss.

There is slight sexual dimorphism between the sexes of the Altai weasel. The male body length from head to body is about 8.5–11 in (220–280 mm) with his tail adding on about 4–6 in (100–150 mm). Males can weigh 8–12 oz (230–340 g). On the other hand, the females are slightly smaller with their head to body length measuring around 8.5–10 in (220–250 mm) with their tail adding 3.5–5 in (89–130 mm) and they weigh around 4–8 oz (110–230 g). This species undergoes seasonal molts during the spring and autumn. The summer coat consists of fur that is gray to gray-brown with some light yellow while the winter fur is more of a dark yellow with some brown. In both coats, the under belly is pale yellow to creamy white.The upper head between the muzzle and ears is usually darker gray-brown. The tail may be more rufous than the back. the summer fur is gray to gray-brown with some light yellow. Their lips are white and the chin has grayish brown vibrissae.