Question: 20 people have lost their lives searching for what mine, Lost McLeod Mine or Northland Pyrite Mine?
Context: The Northland Pyrite Mine, also known as James Lake Mine, Rib Lake Mine, Harris Mine or simply Northland Mine, is an abandoned underground mine in Northeastern Ontario, Canada, located on the southwestern shore of James Lake in Best Township of Temagami.  It was operated by the Northland Mining Company during the early 1900s with the construction of a 91 m shaft and many open-cuts north of the shaft.  Minerals present at the mine include chalcopyrite, pyrite and pyrrhotite, deposited in Precambrian volcanic rock of the Canadian Shield. Hickory Ridge is an extinct unincorporated town in Prince William County, Virginia.  The town was located on land that is now part of Prince William Forest Park, a National Park Service property located adjacent to Marine Corps Base Quantico.  The town was established shortly after the opening of the now defunct Cabin Branch Pyrite Mine in 1889 and was home to many of the mine employees. Lousal mine was a pyrite mine in Portugal.  The mine was opened in 1900 and closed in 1988. Cabin Branch Pyrite Mine Historic District is a national historic district located at Prince William Forest Park, Triangle, Prince William County, Virginia.  It encompasses 4 contributing sites and 42 contributing structures associated with the Cabin Branch pyrite mine.  The pyrite mine opened in 1889, and remained in operation until 1919 or 1920.  The property includes a number of capped mine shafts, and the remains of a commissary building and an old mill; and mine structures, including crusher house, mill, mechanical and support buildings, numerous rail lines. Ridgemont is one of Oakland's relatively newer affluent neighborhoods in the city's upscale hillside districts, this one located next to Merritt College along Campus Drive.  First developed in the 1970s and 1980s as a tract-home development, albeit one tailored to affluent buyers, the neighborhood's stock of large tract homes has expanded to include exceptional custom estates and mansions perched on the neighborhood's choicest ridges, which offer expansive, uninterrupted views of the south San Francisco Bay.  One of the last undeveloped hillside parcels in the city of Oakland, this district has in recent years added a new, less exclusive subdivision on the western slopes below Campus Drive.  Begun in 2005 by Desilva, a real estate developer, this latest subdivision has nearly completed its first phase of homes on the ridge where the Leona quarry (also known as the Alma pyrite mine) was once in use.  The higher-priced segment of this latest subdivision has, as of 2016, begun to break ground on the restored upper reaches of the former quarry, which has undergone extensive environmental repair in preparation for the new subdivision.  During the early 2010s, the country's continuing economic challenges in general, and the depressed housing market in particular, had slowed the pace of sales of existing units and the construction of the more upscale segment of the project.  With the country's improved economic status by 2016, particularly for the affluent, and notably the ongoing, rapid citywide revitalization (some say "hypergentrification") of Oakland, this development's home sales and additional construction have revitalized as well.  Nevertheless, the undeveloped upper hillside of the former quarry –– even after having undergone extensive seeding and terraced hillside reconstitution –– is still visible for miles, even as far away as San Francisco across the Bay. The Greenwood gold mine operated in Prince William County, Virginia, United States, near the town of Independent Hill for a few years before closing in 1885.  It was one of two known gold mines in Prince William County, the other being the Crawford placer prospect on Neabsco Creek, near I-95, though small amounts of gold were occasionally found at the Cabin Branch Pyrite Mine in nearby Dumfries. The 2009 Handlová mine blast occurred on 10 August, 2009 roughly 330 metres (1,080 ft) underground in Trencin Region, Slovakia at Hornonitrianske Bane Prievidza, a.s.s (HNB) coal mine located in the town of Handlová.  20 people were killed, nine others suffered minor injuries and were taken to hospital for treatment.  Some historians have called the disaster the largest mining tragedy in Slovakia’s history.  The deadly explosion, probably caused by flammable gases, occurred after mine rescuers had earlier been deployed to extinguish a fire in the Eastern shaft of the mine. The Løkken Mine is and underground pyrite mine located in the municipality of Meldal in Sør-Trøndelag, Norway.  The mine was operative from 1654 to 1987, from the mining community Løkken Verk.  It contained the largest deposits of its kind in Norway.  Between 1654 and 1845, a total of 11,300 tons of copper was produced from the mine.  From 1904 the mine was run by the company Orkla Grube-Aktiebolag, and until 1987 a total of 24 million tons of pyrite was produced from the mine.  In addition to sulphur, the pyrite contained about 2% copper, in addition to zinc and traces of silver and gold.  The products were originally transported to the sea by horse and sledge during winter time.  From 1908 the ore was transported by the Thamshavn Line, which was the first electrical railway line in Norway.  The annual production was about 350,000 tons of ore during its final years. Davis, Massachusetts is the abandoned location of the "Davis Pyrite Mine".  located in the town of Rowe, Massachusetts.  Once the largest iron pyrite-mine in Massachusetts, Davis grew to be a decent sized mining village at the beginnings of the Second Industrial Revolution (1870–1915).  But, in 1911, a non-fatal collapse of the mine due to “poor mining practices” ended the nearly 30-year run.  By 1937, the mining camp had faded, and all that remained were a blacksmith shop and about 150 cellar holes. Lost McLeod Mine is a legend of a lost mine in the Northwest Territories of Canada.  The story has been featured in many books and magazines.  The events in the legend have led to geographic locations in the Northwest Territories being named Headless Valley and Headless Creek located in Nahanni National Park Reserve.  A creek called Sheep Creek was renamed McCleod Creek in honour of the Mcleod Brothers.  20 people have lost their lives searching for The Lost McLeod Mine.
Answer: Lost McLeod Mine