Ilmakiur is a barometer made of stone. The stone barometer changes its color depending on the advancing weather and is used for predicting the weather. Ilmakiur has been written about in many books from the 1800s. The stone barometer was discovered in Finland and is located in the northern part of that country.
Ilmakiur is also called the "weather stone".

Use

Ilmakiur turns black or grayish when it is going to rain.
The stone shows white spots when it is going to be fine weather. In the 1800s it was believed the rock was a fossil made of clay, ammoniac, rock-salt and saltpeter.
The stone was thought to attract dampness from the atmosphere. If the weather was good Ilamiur would dry out and the salt would appear as the white spots. Modern scientists say the rock is a fossil of potassium nitrate and rock salt.