[FredZarguna]

If it's 3 long tons, then about 0.155 cubic meters (1/7 of your guess, roughly), or around 20 inches/side.

1 m³ water = 1000 kg. Specific gravity of pure gold is 19.32. So 3 * 1000 / 19.32 = 0.155 m³.

Nominally ~$110 million. Although the coins are worth more than the current price of gold.

[21twelve]

A 20-inch cube? That can’t be right. Why just this morning I was watching Gunsmoke, and the guy tossed a chest of gold off the train and into the buckboard five feet away!