Protesting Spanish miners clashed with police in the northwestern town of Caborana on Friday.
The miners form one of two groups participating in a so-called “Black March” to the capital, Madrid.
The other is marching from Spain’s northeast and both are set to arrive on Tuesday.
The miners are unhappy about the scrapping of government subsidies to the industry.
Union leaders moved to downplay the incident, which left two policemen injured.
“We are not trying to get anyone’s attention by clashing with police. I think we need first of all to try to be smart, to be able to manage the problem where it actually is, so the news is not about violence,” said Maximino Garcia of the CCOO union.
Spain’s mining industry has been in decline for the past two decades.
Forty mines are open today, employing some 8000 people.
The European Commission has ruled the subsidies amount to illegal state aid and must disappear completely by 2018.