The Tsarevo-Aleksandrovskii gold mine, later known as Mariinskii and Leniskii gold mine, is an important historical mine located in Leninsk village, along the Tashkurganka riverlet. The mine is situated in a gold-bearing field that encompasses a range of veins and placers derived from their breakdown. Mining techniques, both underground and surface, were employed in the belt around a granitoid massif that was elongated in the meridian direction and pinching out at its north and south edges against belts of limestones and serpentinites.
One of the unique features of this gold-bearing field is the quantity of large gold nuggets recovered, numbering more than 2000. The biggest nugget ever found in Russia, known as “The Great Triangle,” was discovered in 1842 by 18-year-old gold prospector Nikifor Syutkin. This nugget, weighing 36,015.7 grams, is currently preserved in the Diamond Fund, located in the Kremlin Armoury building in Moscow.
Gold was first discovered in the Tashkurganka placers in 1823, and within a year, a dozen nuggets weighing between 2 to 8 Russian pounds were recovered. Over the years, larger nuggets were discovered, with Ozerskii mentioning five nuggets weighing from 13 to 24 Russian pounds. The largest nugget ever found in Russia, “The Great Triangle,” was recovered in 1842, weighing 36,015.7 grams after being cleaned from gangue minerals. In 1854, a nugget weighing 20.1 kg was found approximately 700 meters from where “The Great Triangle” was recovered. In 1882, another nugget weighing approximately 20 kg was discovered. The sources of these nuggets are the quartz veins mentioned above, some of which contained gold nests that could reach several kilograms in weight. For example, in vein no. 2 of the “Vasyaniskoe” sector, two gold nests were identified, yielding 8.99 and 12.6 kg of metal, respectively (Smolin, 1970).