is one of the 100 Famous Japanese Mountains. The 2354 m (7,723 ft) high peak lies, on the border of Nagano Prefecture

Nagano Prefecture

is a prefecture of Japan located in the Chūbu region of the island of Honshū. The capital is the city of Nagano.- History :Nagano was formerly known as the province of Shinano...

 and Gunma Prefecture

Gunma Prefecture

is a prefecture of Japan located in the northwest corner of the Kantō region on Honshu island. Its capital is Maebashi.- History :The remains of a Paleolithic man were found at Iwajuku, Gunma Prefecture, in the early 20th century and there is a public museum there.Japan was without horses until...

. There exist alternative spellings of the mountain's name, like: 吾妻山 and 吾嬬山 which is read as "Agatsumayama" (Mount Agatsuma). In the village Tsumagoi

Tsumagoi, Gunma

is a village located in Agatsuma District, Gunma, Japan.As of September 1, 2007, the village has an estimated population of 10,743 and a density of 31.19 persons per km². The total area is 337.51 km².-Geography:...

, the mountain is spelled 吾妻山.

The mountain should not be confused with of which there are two, one in Nagano Prefecture and the other in Saitama Prefecture

Saitama Prefecture

is a prefecture of Japan located in the Kantō region of the island of Honshu. The capital is the city of Saitama.This prefecture is part of the Greater Tokyo Area, and most of Saitama's cities can be described as suburbs of Tokyo, to which a large amount of residents commute each day.- History...

. Though the reading is the same, the name written in Kanji

Kanji

Kanji are the adopted logographic Chinese characters hanzi that are used in the modern Japanese writing system along with hiragana , katakana , Indo Arabic numerals, and the occasional use of the Latin alphabet...

 differs from the mountain in this article.

Outline

Mount Azumaya was formed between 900,000 and 300,000 years ago by andesite

Andesite

Andesite is an extrusive igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture. In a general sense, it is the intermediate type between basalt and dacite. The mineral assemblage is typically dominated by plagioclase plus pyroxene and/or hornblende. Magnetite,...

 lava flowing out of a Stratovolcano

Stratovolcano

A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...

. An eruption 340,000 years ago formed a caldera of circa 3 kilometers in diameter. Through erosion the mountain has arrived at its present form with several peaks. is the general term for the following peaks lying roughly on a circle: , Mount Azumaya, , .

The famous Sugadaira Kōgen ski area is found on the mountains's southwest (Nagano-) side. Also on the Gunma-side there exists a ski area. In addition, north of the mountain lies which is one of the 100 Selected Japanese Waterfalls.

Main ascent routes

The mountain is well connected with several hiking trails: - - Mount Azumaya - Mount Azumaya - Mount Azumaya - Mount Azumaya

The gondola from Palcall Tsumagoi is also operating during the summer season and can be used to climb the mountain

External links

• Mount Azumaya at the National Institute of Advanced Industrial Science and Technology
  National Institute of Advanced Industrial Science and Technology
  The , or AIST, is a Japanese research facility headquartered in Tokyo, and most of the workforce is located in Tsukuba Science City, Ibaraki, and in several cities throughout Japan. The institute is managed to integrate scientific and engineering knowledge to address socio-economic needs...
  
  , Geological Survey of Japan
• Topographic map (1:25,000)
• Nagano's 100 best highlights (長野の大地みどころ１００選)