A lode is a vein or deposit of metal ore found in rock, usually discovered through mining. When miners in the 1800s struck a rich lode of gold or silver, they had found a concentrated band of valuable metal running through the mountain. The famous Comstock Lode in Nevada, discovered in 1859, contained massive amounts of silver and gold that made many miners wealthy.

Miners would follow the lode deeper into the earth, extracting the ore as they went.

You'll most often hear lode in the phrase mother lode, which means an especially rich deposit of ore or, more broadly, an abundant source of something valuable. If you discover a library with thousands of comics in the basement, you might say you've hit the mother lode. Finding your grandmother's attic full of antique toys could be the mother lode of treasures. The phrase captures the excitement of discovering more of something good than you ever expected.