(Recasts throughout, updates with economic impact, fresh quotes, color, detail on mounting protests)
By Dave Sherwood and Fabian Cambero
SANTIAGO, Oct 29 (Reuters) - Chileans took to the streets again on Tuesday, pouring by the thousands into plazas and shutting down main boulevards in a sign that government promises of reform continued to fall short.
Police in armored trucks watched over the gathering masses. The night before, vandals wreaked havoc nearby, looting, setting fires and sowing chaos amid a melee of sirens, protesters banging pots and heavy black smoke.
President Sebastian Pinera's newly appointed spokeswoman Karla Rubilar condemned the previous night's mayhem, saying it did not reflect the wishes of the majority.
"The violence is over-taking the legitimate demands of the social movement," Rubilar told reporters. She called on all Chileans, from soccer players to cultural icons, to reject the rioting.
Days earlier, more than a million Chileans marched peacefully against inequality in Santiago, the largest protest since Chile's return to democracy in 1990.
The continuing unrest in Chile follows a week of riots, arson and protests over inequality that have resulted in at least 18 dead and 7,000 arrested, prosecutors said. Chilean businesses lost more than $1.4 billion. The city's metro suffered nearly $400 million in damages.
Pilar Zofoli, a 30-year-old schoolteacher, said the violence and destruction to public spaces and services was making life miserable for Santiago's working class.
"I support this cause, but I don't like the way things are going," she said. "In the end, this affects us, not the rich."
Protests over a hike in metro fares spun out of control earlier this month, prompting Pinera to pledge sweeping social and economic reforms, and to upend his cabinet.
Chile, the world's top copper producer, has long boasted one of Latin America's most prosperous free-market economies. A plummeting copper price and global trade tensions, however, have dragged on the export-dependent economy and exposed entrenched inequality.
A putrid blend of smoldering fire from an overnight blaze downtown and tear gas hung heavily over Santiago through much of Tuesday. Chileans in business attire wore makeshift masks or wet towels over their faces as they headed to and from work. Many schools and businesses remained closed, or shut early.
Catalina Barrera, an 18-year-old high school student, said she felt Pinera's announcements had missed the mark. The protests would go on, she said.
"If, after that massive march on Friday, we get nothing but a cabinet change in which they continue to nominate more of the same people, then violence is our only option," she told Reuters.
Students, unions and other social groups have joined the Chile protests in massive numbers, but a leader or spokesperson has yet to emerge. Chile's fractured opposition parties have supported the demonstrations but have not led them, leaving a power vacuum that has hindered negotiation with the masses and left little end in sight.
"So much damage, so many jobs lost, and so many people behind it all," said Ruben Saltibanez, a maintenance worker at a building partially razed in an arson attempt. "It's getting hard to take."
A U.N. spokesman on Tuesday said its human rights office was very concerned by the violence and destruction, and said it would soon send a mission to Chile to investigate human rights abuses.
The protests have ground Santiago to a near halt for more than a week. Rioters have looted more than 600 businesses, including many supermarkets and electronics shops. An iconic mall and shops in the mirror-windowed Costanera Center, South America's tallest building, remained closed Tuesday.
Chile's all-important copper and lithium mining industries had seen varying degrees of impact as of early this week.
BHP told Reuters late Tuesday its Escondida copper mine, the world's largest, was operating at a reduced rate after union workers walked off the job for part of the day.
Elsewhere, copper miners said riots had otherwise mostly spared production, though continuing protests had hobbled port facilities, public transportation and supply chains, impacting operations.
Indigenous protesters had for several days last week blocked access to lithium miner SQM's operations in the Atacama salt flat, one of the world's richest reserves of the ultralight battery metal.
SQM declined to comment on the impacts of the blockade.
(Reporting by Dave Sherwood; Additional reporting by Natalia Ramos and Fabian Cambero in Santiago, and Stephanie Ulmer-Nebehay in Geneva; Editing by Bernadette Baum and Lisa Shumaker)