The Alaskan mining project Pebble, potentially the world's biggest multi-metal mine containing an estimated 80.6 billion pounds of copper, 5.6 billion pounds of molybdenum, and 107.4 million ounces (Moz) of gold resources, is one of the most controversial mining projects in the US. The project is embroiled controversy due to its location in the Bristol Bay Region in south-west Alaska, a major fishing area known as the "America's fish basket".

Controversy surrounding the project started with resistance from local tribes and fishing community centres that fear waste from the mine will endanger salmon and other fisheries in the region. The US Environmental Protection Agency (EPA), which conducted a watershed assessment study of the Bay Area, has also raised concerns about significant potential environmental threats posed by the project towards local habitats and the salmon fishery. About 84 percent of Alaskans who commented on EPA's watershed assessment were against the mine.

Project partner Anglo American's withdrawal from the controversial mine towards the end of the year further added to the uncertainty over Pebble project. The project is currently 100% owned by Northern Dynasty and has been in exploration and environmental study phase since 2007. More than $556m was spent on the project as of September 2013 but the project requires a range of key regulatory permissions before production can start.

Controversy surrounding Pascua-Lama gold-silver project located in the Andes Mountains, straddling the border of Argentina and Chile, culminated with developer Barrick Gold suspending the project altogether in 2013. The Chilean section, which accounts for about three fourth of the total project area attracted far-reaching controversy and public protests due to potential impact on glaciers present in the mine's vicinity. Eventually the Chilean Court issued an order to stop the project development in April 2013.

The Chilean Environmental Authority (SMA) demanded Barrick Gold address environmental threats posed by the project, such as the glacier run off, the impact on the delicate mountain wetland system and the vulnerability of the Diaguita indigenous community. The project cost, initially estimated at $3bn, rose around $8.5bn as a consequence of the environmental complications.

These environmental hurdles coupled with the difficulty in securing subsidised project loans finally led Barrick Gold to shelve the Pascua Lama project in October 2013. About $5.4bn had already been spent on the project, which was estimated to contain 17.9Moz of gold and 676Moz of silver in reserves.

Rosia Montana, Romania

The Rosia Montana silver and gold mining project in Romania, one of the biggest mining ventures in Europe, created public outcry in 2013 when thousands of Romanians took to the streets to protest against Rosia Montana Gold Corporation's (RMGC) plan to reopen an ancient gold and silver mine.

Protests flared up after the Romanian government approved draft legislation in August 2013, declaring Rosia Montana a project of national interest and entrust RMGC with extraordinary powers to go ahead with the project. Those against the project fear environmental damage caused by cyanide used for extracting the gold also alleging that the project would destroy the oldest Roman gold mine galleries in the world, a site that otherwise qualify as an UNESCO World Heritage Site. The Romanian Senate, based on the recommendation of a special Parliamentary Commission, rejected the draft law pertaining to the approval of the controversial gold project in November 2013.

Controversy over Rosia Montana continued into 2014 with reports of the Romanian Government working on a new generic mining law which may still leave the door open for the gold project. It is also anticipated that RMGC might proceed with Rosia Montana by devising a new proposal for the mine's development. More than $400m was spent on the open cast gold and silver mining project that covers the town of Rosia Montana and the four surrounding mountains in Transylvania, northern Romania. Proven and probable reserves at Rosia Montana were estimated to be 10.1Moz of gold and 47.6Moz of silver.

AngloGold Ashanti's La Colosa gold project located in the Tolima district of Colombia, about 150km west of the capital city Bogota caused significant resistance by local communities and vehement criticisms from international human rights organisations including the Colombia Solidarity Campaign, over environmental issues.

Opposition to the project centred on the impact of pollution and allegations that the use of water resources by the proposed gold processing plant of the project at Piedras municipality would affect agriculture and communities in the vicinity. Farmers from Piedras demonstrated in protest against the project in February 2013 and five months later a referendum was conducted, in which 2,971 out of 3,007 Piedras voters voted against the project.

The La Colosa project, containing 24Moz of gold resources at an average grade of 0.9g/t to 1.0g/t Au by 2012 estimates, is yet to receive the permission from the Colombian Minister of Environment. The mine was initially scheduled to commence production in 2016 but this has been delayed until the end of 2019. AngloGold Ashanti had invested over $255m in the project by the end of 2013.

Skouries gold project, Greece

The controversy over the Skouries gold mine project being developed by Hellas Gold, a subsidiary of the Canadian gold producer Eldorado Gold, near the village of Skouries in Halkidik peninsula in northern Greece, also made headlines in 2013 over environmental concerns. Thousands of people took to streets protesting against the $1.32bn gold mining project which is thought to contain over 5.3Moz gold in reserves.

Protestors allege that the project threatens to contaminate groundwater supplies and pollute the air with toxic heavy metals including cadmium, lead, arsenic and mercury, destroying 180 hectares of forest and affecting the livelihood of local natives who are dependent on income from tourism, fishing, farming and beekeeping. Protests, which started in 2011, eventually sparked a series of rallies and police crackdowns in 2013.

The human rights organisation Amnesty International questioned the use of intimidation and human rights violations committed by the state authorities in dealing with the protestors. Ecologist Greens, a Greek Green ecologist political party, invited its Canadian counterpart, the Green Party of Canada (GPC), to investigate and stop the Skouries gold project as well as another controversial mining project the Perama Hill gold mine which is also being developed by the same miner in Thrace, Greece.