What would happen if you tried to roast marshmallows over Mount Etna's lava?

If you tried to roast marshmallows over Mount Etna's lava, the experience would be dramatically different from what most people imagine, and almost certainly fatal if you got close enough to actually attempt it. The primary problem is not the lava itself but the environment surrounding it. Lava flows from Etna typically range in temperature from about 700 to 1200 degrees Celsius, which is far hotter than any campfire. At those temperatures, the radiant heat alone would be lethal at relatively close distances, causing severe burns to exposed skin and igniting clothing before you could even extend a marshmallow on a stick toward the molten rock. The gases surrounding active lava are another enormous hazard. Volcanic lava releases sulfur dioxide, carbon dioxide, hydrogen sulfide, and other toxic gases in significant quantities. Breathing these gases even briefly can cause respiratory damage, and in higher concentrations they can be immediately incapacitating or fatal. Etna is one of the most active volcanoes in Europe and constantly emits these volcanic gases even when not in a major eruption phase. The combination of toxic fumes and extreme heat would make sustained proximity to the lava essentially impossible without specialized protective equipment, and even with such equipment, getting close enough to roast a marshmallow would be extraordinarily dangerous. Assuming you somehow survived long enough to hold a marshmallow near the lava, the marshmallow would not roast in the pleasant, golden-brown way you might hope. The intense radiant heat would cause it to ignite almost instantly rather than slowly caramelize. Sugar begins to caramelize around 160 degrees Celsius and burns well before you reach lava temperatures, so the marshmallow would simply catch fire and incinerate within seconds. The wooden or metal stick you were using would also likely ignite or melt depending on the material, and any synthetic materials nearby would release their own toxic fumes as they burned. There is actually a somewhat famous and cautionary piece of science communication around this topic. Volcanologist Carolyn Prentice and others have pointed out that people sometimes romanticize the idea of cooking food over lava, but the reality is that lava is not like a very hot campfire. A campfire radiates heat in a manageable way and you can control your distance. Lava flows also move unpredictably, can crust over and then break through, and can release sudden bursts of gas. People have been killed approaching lava flows even at what seemed like safe distances, either from unexpected surges, toxic gas pockets, or lava spattering from lava tubes breaking open underfoot. The marshmallow itself would also likely be contaminated before it even got close to the lava. The particulate matter in volcanic emissions, including tiny glass-like shards of volcanic ash, would coat any food exposed to the air near an active vent. So even setting aside the fire, the toxic gases, and the lethal heat, you would end up with a chemically contaminated, ash-covered, incinerated lump rather than a toasted treat. The entire scenario is a good illustration of how human intuition about scaling up familiar experiences, like thinking lava is just a really big campfire, tends to break down completely when confronted with the actual physics and chemistry of extreme natural phenomena.