The stocks and expositions of the museum are enriched by the means of:

• Buying samples from leading mineral trade companies: Dr. F. Krantz – Bonn; Al. Stuart Co. – Paris; B. Sturtz – Bonn; Grebel, Wendler&cie – Geneva; Mineralienhaus Droop – Dresden; Julius Bohm – Wien; Foote Mineral Co – Philadelphia; Steeg&Renter – Berlin; A. H. Petander – Helsingfors;

• Donations from famous scientists and mineralogists: Prof. Berwerht – Wien; Prof. Lacrua – Paris, M. Dorfman – the Mineralogical Museum of Fersmana, Dr. Fischer - Berlin, Dr. Kruta – the Museum of Moravia, A. S. Paravenah - Kiev, Prof. E. M. Spiridonov - Moskow, Prof. V. Vergilov, Prof. Bogdanov – Sofia; from lapidaries and others;

• Collecting and researching by teachers and students from the Mineralogy, Petrography and Mineral Resources Department” – “… The collections of the Institute over the last year were filled up mainly by local (Bulgarian) materials, collected by the personnel during their tours in various parts of the country” – as written in the report of Prof. N. Nikolov, the curator of the Institute in 1926-1927.

The samples are drawn up in inventory and are organized in collections by name, type and country:

• The richest collection is the “Krantz” collection, which contains 2280 minerals and 2100 petrography samples;

• Historic interest present the “Acad. G. Bonchev” collection with 72 samples, gathered and drawn up in the period 1898-1940;

• The “Beril” collection contains 106 samples, 73 of which are obtained from Bulgarian Deposits.