The masters, or owners, of mining rights for the exploration of ores were prospectors and free or independent prospectors. Concession books and registers were kept about the proprietors of ore fields or mines. In them was entered, among other things, which ore was planned to be exploited. The possessor of a licence, permits for exploration and exploitation of ores, paid a certain fee every year. He could also sell his mining righis. in the shape of permits, partially or, more frequently, totally, as was recorded in the books. If he did not pay taxes, he could lose all his rights, which were then deleted, or crossed out of the mining books. Those who possessed mining permits had to solve the questions of compensation to the owners of the lands where they intended to do detailed explorations, and to exploit the ore, even to the extent of leasing or buying the land. The mining activity in Croatia between the mid-19th and mid-20th centuries is richly documented in the (Imperial and Royal) mining captaincies in Zagreb, Zadar and Split. The basic mining law was the General Austrian Mining Law of 1854, with its amendments of 1911 (Legal Article VI about mineral oil substances and natural gases). In Croatia, mining enterpreneurs were individuals or companies (including the slate) with the proviso that at the beginning there were more foreigners. However, Croatian traders, industrialists, magnates, officials, bankers, various companies, engineers, artists, retired persons, peasants, officers and others soon became involved in mining. Among the entrepreneurs there were various noblemen. It has been ascertained in this research that in individual periods between 1855 and 1945 there was a dominance of individuals (mainly 81%-85%) while today (1990-1995) it is quite the opposite (86% are companies), because this is the end of the long term control of the socially owned companies. Thes same situation obtains today with respect to exploitation licenses, where companies predominate (84%).