Ijen Volcano

Ijen Volcano (2,799 m) is a group of volcanoes on the border of Banyuwangi Regency and Bondowoso Regency in East Java Province, Indonesia. This mountain last erupted in 1999 and a crater lake on the summit is known as the largest acidic water lake in the world.

Mount Ijen is an active type A volcano that grows after the Ijen Caldera with a height of 2,443 meters. At the top of Ijen lay a panorama of other mountain scenery in the Ijen Mountains complex including the summit of Mount Merapi East Java, Mount Raung, Mount Suket, Mount Rante, and others.

Ijen crater

Many cones and craters are inside the caldera or along the edges. The largest concentration of post-caldera cones to the east-west crosses the south side of the caldera. The active crater on Mount Ijen has a length of 900 meters, width of 600 meters, depth of ~180 meters, volume of 30 million cubic meters and PH ~0.5.

Turquoise crater lake is the largest acidic lake in the world and water seeps through the western wall to form the Banyupahit River for 40 kilometers to Asembagus. Tertiary impacts on irrigation, water quality and community wells contaminated with F. Water well survey data shows 60% contain F over WHO recommendations which have significant dental fluorosis (~70%).

The very acidic lake formation in the Ijen Crater is related to the formation of the Ijen Caldera by the massive eruption of the Old Ijen strato volcano or Mount Kendeng (~4,000 meters) around 300,000 to 50,000 years ago. This old Ijen mountain has only one vent based on the oval caldera shape.

This Ijen Caldera is 16 kilometers in diameter and elliptical in shape where the northern wall curves to the south. The southern caldera wall is mostly covered with eruption of volcanic deposits as many as 22 active volcanic cones after the caldera.

Blue Fire

Every morning at 2:00 to 4:00 in the vicinity of the crater comes the phenomenon of blue fire which is the uniqueness of this place. This blue flame is lit by sulfur gas that emerges from cracks at temperatures up to 600 Celsius (1,112 Farenhiet).

Fire can be as high as 5 meters (16 feet), while some gases condense to become liquid and still burning. Ijen Crater is the largest blue fire area in the world.

Sulfur mining

Active ventilation on the shores of the lake is a source of sulfur and supports mining operations. Volcanic gas that passes through is channeled through ceramic pipelines to produce condensed liquid sulfur. Sulfur, which is dark red when melting, flows slowly from the end of the pipes and ponds on the ground, turning bright yellow when cold.



The miners break down the cooled material into large pieces ranging from 75 to 90 kilograms (165 to 198 lbs) to be carried in baskets up to 300 meters (980 feet) to the edge of the crater with a slope of 45 to 60 degrees and then 3 kilometers (1,9 miles) to go down the mountain to get paid.

Most miners take this trip twice a day. A sulfur refinery pays miners with the weight of sulfur transported. At least 200 miners extract 14 tons per day or about 20% of sustainable daily deposits.