Washington Monument aluminum apex

Brief historical anecdote — aluminum pyramid at the top of the Washington Monument as a lightning rod, made of aluminum because at the time (1880s) it was more valuable than gold.

Before that, aluminum was more expensive than gold. The crown jewels of the French royal family included aluminum dinnerware because it was so unique and the more valuable material. The top of the Washington Monument has a little aluminum pyramid as a lightning rod — at the time it was more valuable than gold. So in 1888 Hall and Héroult developed this process. Pure aluminum is very soft, so you have to strengthen it — six or seven ksi otherwise.