Crushing Lava Rock To Get Gold

Crushing Lava Rock To Get Gold: Geology’s Hidden Treasure Hunt

The image of crushing volcanic rock to extract gleaming gold captures the imagination – a direct path from Earth’s fiery depths to precious metal. While the process isn’t quite as simple as smashing any old lava rock you find, there is fascinating geology and hard science behind this concept.

The Geological Genesis: Gold in Volcanic Terrain

Gold doesn’t originate within the molten lava itself during an eruption. Instead, its journey often begins deep below active volcanic zones. Here’s how it typically happens:

1. Hydrothermal Solutions: Superheated water circulates deep underground, dissolving trace amounts of gold and other minerals from surrounding rocks.
2. Volcanic Plumbing: This mineral-rich fluid travels upwards through fractures and faults associated with volcanic systems – essentially using the volcano’s “plumbing.”

3. Deposition: As the hot fluid rises and cools, or reacts chemically with different rocks it encounters (like porous lava flows or breccias), pressure drops and conditions change. This forces the dissolved gold to precipitate out of solution.
4. Host Rocks: This precipitation often occurs within cracks (veins), pore spaces in volcanic rocks (especially breccias – fragmented lava), or along contacts between different rock types formed during volcanic activity.

Therefore, while fresh surface lava flows rarely contain significant gold, older volcanic rocks can be important hosts for gold deposits formed by these later hydrothermal processes.

Why Crush? Liberating the Tiny Treasure

Gold found in these volcanic-hosted deposits is usually microscopic or locked tightly within minerals like quartz veins running through the rock massivly larger than the gold particles themselves. You can’t simply pick it out by hand.

This is where crushing comes in:

1. Size Reduction: Large chunks of rock must be broken down into progressively smaller fragments.
2. Liberation: The goal is to break apart the host rock matrix enough to physically separate (“liberate”) the tiny particles of free gold or expose them sufficiently for chemical processing.

3. Processing Pathway: Once liberated through crushing (and often grinding into fine sand or powder), further methods like gravity separation (using water and sluices), flotation (using chemicals to make gold repel water), or cyanide leaching are used to concentrate and recover the actual gold.

The Reality Check: Scale and Economics

While scientifically sound, crushing lava rock for individual prospectors hoping to strike it rich is generally impractical: