1. Stone knife
Hammer Grab a spherical hunk of hard, dense rock that fits in the palm of your hand (granite is ideal).
Core Now the hard part: Good blade material such as flint, chert, slate, obsidian, or jasper can be tough to find and identify. Break open stones and look for smooth, ceramic-like grain and arcing, cone-shaped fracturing patterns. Search areas like water edges or cliff bottoms.
Pro tip Clack potential stones together and listen for a high-pitched ring. The closer it sounds to glass, the better a candidate the stone is for a core.
Best uses Razor-thin blades can slice meat, gut fish, and cut cord; when blades go dull, use them to scrape wood for tinder. Larger heads can saw through sticks and even chop wood for fire- or shelter-making.
Key Skill Flint knapping
Chuck a core stone against a boulder. If you’re short on time, the resulting fragments can suffice. To make a formidable, longer-lasting knife, use this technique. (1) Select a half-inch to inch-thick shard to hone. From a sitting position, brace your forearm on your thigh and hold your rough blade parallel to the ground with the edge facing out. (2) With the hammer stone in the other hand, strike a downward, glancing blow on the edge, following through. Sufficient force will break flakes off the bottom of the shard. (Wear shades—or blink when you strike, if you have none—to keep stray chips out of your eyes.) (3) Flip your blade rock and strike flakes off the opposite side. Continue flipping and striking until the blade is sharp enough to shave a fingernail. Pro tip Push a pointed rock or hardened wood along the edge to file off smaller bits.