Unknown letter of L. A. Popugaeva from the archive of professor D. P. Grigoriev

The article publishes previously unknown documents about L. A. Popugaeva from the personal archive of Professor D. P. Grigoriev, stored in the Commission on the History of the Russian Mineralogical Society: her letter from Nyurba dated August 5, 1956, a letter from VSEGEI with a request for guidance of a graduate student L. A. Popugaeva, a letter from CNILKS with a request for consultation signed by L. A. Popugaeva herself, as well as agendas for meetings of the Mineralogical Society and dissertations on the diamond problem. All documents are original, attributed and chronologically correlated with previously published documents. They are very valuable for the history of mineralogy as actual evidence of distant events. First of all, the documents mark the main stages of the life and scientific activity of an outstanding geologist, the discoverer of indigenous diamonds in Yakutia, L. A. Popugaeva. Secondly, they show her activity in the last professional field - the study of gemstone raw materials of the North-West Russia, mainly the Kola Peninsula. The article is dedicated to the date of the untimely death of L. A. Popugaeva.