English: Red-brown microcrystals of ponomarevite, an extremely rare K-Cu chloride from the famous Tolbachik volcano (Tolbachik Volcano, Kamchatka Krai, Russian Federation) the only known locality and associated to green crystals of klyuchevskite. The ponomarevite crystals are difficult to see in the photo. The sample is stored in a closed vial to avoid decomposition in the air atmosphere. Ex Vandenbroucke Museum collection from Waregem, Belgium.