The Mont Blanc massif is popular for outdoor activities like hiking, climbing, trail running and winter sports like skiing, and snowboarding.

The three towns and their communes which surround Mont Blanc are Courmayeur in Aosta Valley, Italy; and Saint-Gervais-les-Bains and Chamonix in Haute-Savoie, France.

The 11.6 km (7+1⁄4 mi) Mont Blanc Tunnel, constructed between 1957 and 1965, runs beneath the mountain and is a major transalpine transport route.

Mont Blanc and adjacent mountains in the massif are predominately formed from a large intrusion of granite (termed a batholith) which was forced up through a basement layer of gneiss and mica schists during the Variscan mountain-forming event of the late Palaeozoic period.

His list, entitled "Statistique minéralogique des environs du Mt-Blanc", catalogued 90 mineral types although it also included those present only as very small components of rocks.

[6] If these are excluded, it is known today that at least 68 separate mineral species occur across the wider range of the Mont Blanc massif.

However, at an even higher altitude (near the summit of Mont Blanc), precipitation is considerably less, with only around 1,100 mm (43 in) recorded, despite the latter measurements being taken at the height of 4,300 m (14,100 ft).

[14] He tried to summit it with the Courmayeur mountain guide Jean-Laurent Jordaney, a native of Pré-Saint-Didier, who accompanied De Saussure since 1774 on the Miage Glacier and Mont Crammont.

The first recorded ascent of Mont Blanc (at the time neither within Italy nor France) was on 8 August 1786 by Jacques Balmat and the doctor Michel Paccard.

This climb, initiated by Horace-Bénédict de Saussure, who rewarded the successful ascent, traditionally marks the start of modern mountaineering.

[21] After the Napoleonic Wars, the Congress of Vienna restored the King of Sardinia in Savoy, Nice, and Piedmont, his traditional territories, overruling the 1796 Treaty of Paris.

[22] Italy claims, that the border was moved by France in 1865, when surveys carried out by a cartographer of the French army, Captain JJ Mieulet, incorporated the summit into French territory, making the state border deviate from the watershed line, and giving rise to the differences with the maps published in Italy in the same period.

[23][24] Modern Swiss mapping, published by the Federal Office of Topography, plots a region of disputed territory (statut de territoire contesté) around the summits of both Mont Blanc and the Dôme du Goûter.

Gustave Eiffel agreed to take on the project, provided he could build on a rock foundation if found at a depth of less than twelve metres (39 ft) below the ice.

The Mont Blanc tunnel would connect Chamonix, France, and Courmayeur, Italy, and become one of the major transalpine transport routes between the two countries.

Renovations include computerised detection equipment, extra security bays, a parallel escape shaft, and a fire station in the middle of the tunnel.

A remote site for cargo safety inspection was created on each side: Aosta in Italy and Passy-Le Fayet in France.

Despite unsubstantiated claims recurring in media that "some estimates put the fatality rate at an average of 100 hikers a year",[41] actual reported annual numbers at least since the 1990s are between 10 and 20: in 2017, fourteen people died out of 20,000 summit attempts, and two remained missing; with 15 in 2018 as of August.

[43] The recent temperature rises and heatwaves, such as those of the summers of 2015 and 2018, have significantly impacted many climbing routes across the Alps, including those on Mont Blanc.

For example, in 2015, the Grand Mulets route, previously popular in the 20th century, was blocked by virtually impenetrable crevasse fields, and the Gouter Hut was closed by municipal decree for some days because of a very high rockfall danger, with some stranded climbers evacuated by helicopter.

[45][46] In July 2014, an American entrepreneur and traveller Patrick Sweeney attempted to break the record with his nine-year-old son and 11-year-old daughter.

[55][56] In August 2014, an unknown Austrian climber with his 5-year-old son were intercepted by mountain gendarmes at 3,200 m (10,500 ft) and forced to turn back.

[57] On 5 August 2017, 9-year-old Hungarian twins and their mother were rescued from 3,800 m (12,500 ft) by helicopter while their father and family friend continued their summit attempt.

[58] The Mont Blanc massif is being put forward as a potential World Heritage Site because of its uniqueness and cultural importance considered the birthplace and symbol of modern mountaineering.

They will serve 30,000 skiers and hikers annually, helping to alleviate the discharge of urine and faeces that spreads down the mountain face with the spring thaw.

[63] Global warming has begun to melt glaciers and cause avalanches on Mont Blanc, creating more dangerous climbing conditions.