One of mankind's oldest and most useful natural materials is solid rock. Working in quarries, rock splitters use skills handed down through the centuries to break large slabs of stone into smaller, more manageable pieces.

This is a trade that's learned on the job from more experience splitters. Hand tools like hammers and metal wedges are used. The wedges are carefully driven deeper and deeper into the rock until it finally splits. Workers also learn how to properly mark the stone for cutting straight lines. These are the same basic techniques the ancient Egyptians used to build their massive pyramids.

Even today, with the help of modern equipment, it's still hard and noisy work. That's why protective gear needs to be worn, including safety glasses, earplugs, and special steel-reinforced boots.

The work is done outdoors in the heat of summer and the cold of winter. It requires bending and lifting, as well as working in awkward positions. As work sites become more mechanized, the need for human rock splitters is expected to decline.

But for those who love physical challenges and have excellent coordination and skill with tools, it's a job that brings its own form of satisfaction. Rock splitters can take pride in handling tasks that relatively few people have the drive, strength, and endurance to perform.