Smoky quartz in combination with Citrine from K2, Afghanistan (Day and night crystal)

The K2 (Urdu: کے ٹو, Kaitu) is an 8611 meter high mountain peak on the Pakistani-Chinese border in the Karakoram. It is the second highest mountain in the world, after Mount Everest. The K2 is considered 'the holy grail' for mountaineers and is according to many experts the most difficult mountain peak in the world to climb. The mountain has a death rate of 25%. For a long time the K2 had no name as the mountain was not immediately visible to the local population. In 1856 the area was surveyed and described by British Colonel Thomas George Montgomerie as part of the Great Trigonometrical Survey. This gave the mountain the abbreviation "K2", because it is the second mountain that Montgomerie encountered in the Karakoram. Montgomerie numbered the mountains in the order he saw them. The other peaks were originally named K1, K3, K4 and K5, but over time these were renamed to Masherbrum, Broad Peak, Gasherbrum II and Gasherbrum I respectively. The reason that the name K2 has remained is the fact that no local name existed. Other but less known names for the K2 are Mount Godwin-Austen, Lamba Pahar ("Long Mountain" in Urdu), Qogir Feng, Chogori or Dapsang. In Balti there is no other name than K2, which is pronounced 'Ketu'.

Smoky quartz is a quartz variety. The color is smoke brown to almost black, translucent. Very dark varieties are called morion. Smoky quartz is most common in cavities in intrusion rocks and high-grade metamorphic rocks. Smoky quartz is rare in sedimentary and outgrowth rocks. Locations include the Alps, Brazil, Russia, Mexico, India, Ireland, Zimbabwe, Afghanistan, and USA. The color of smoky quartz is caused by aluminum in the crystal lattice in combination with ionizing radiation. The aluminum replaces the silicon in the crystal structure, forming the complex [AlO4-] instead of [SiO4]. During the growth of the crystal, to compensate for the difference in charge, small monovalent cations of, for example, hydrogen, lithium or sodium are simultaneously incorporated into the crystal structure. Under the influence of ionizing radiation, the electron from the [AlO4 -] complex moves to a cation and a color center is formed. This process normally only takes place below 50 ° C. At higher temperatures, the breakdown of the color centers takes place faster than their production. The source of the ionizing radiation is usually potassium-40 in the surrounding rock. The color of smoky quartz therefore arises long after the crystals have formed and can take several millions of years. This is also the reason that most smoky quartz forms in feldspar-rich rocks such as granite. When heated above 200 ° C, smoky quartz will lose its color. Irradiating clear quartz (rock crystal) with X-rays or gamma rays almost always produces smoky quartz. The method is therefore used to make smoky quartz from colorless quartz. In ancient times this stone warned soldiers in battle when it turned dark. Smoky quartz is still used for rosaries and crucifixes. A number of medicinal properties are attributed to smoky quartz; it would help against digestive complaints, stress, grief and help with a desire to have children. According to various literature, the mineral belongs to the zodiac sign: Libra.