The state geologist shall cause proper specimens, skillfully prepared, secured, and labeled, of rocks, minerals, ores, coals, fossils, and other earth materials discovered or examined in the course of the geological surveys to be preserved for public inspection free of cost. The state geologist, when practicable, shall cause duplicate specimens in reasonable numbers and quantities to be collected and preserved for the purpose of exchange with or transfer to universities, colleges, governmental bodies, and scientific institutions.