Short answers, pulled from the story.
The oldest known metalworking artifact is a copper pendant discovered in northern Iraq, dating back to 8,700 BCE. This small piece of jewelry represents the dawn of a technological revolution that would eventually build the modern world.
Gold was likely the first metal to be worked because it is found in nature as pure nuggets, requiring no smelting or complex chemistry to shape. A simple stone hammer and anvil were sufficient to turn these nuggets into tools and ornaments.
The transition from pure copper to bronze marked a pivotal moment in human history, occurring around 2700 BCE. While copper was abundant, it was too soft for tools requiring edges or stiffness, so tin was added to molten copper to create the alloy known as bronze.
Unlike gold or copper, iron is significantly more tightly bound to its ore, requiring much higher temperatures to smelt. This process was more difficult and required more advanced technology, but the resulting metal was stronger and more abundant.
Casting is a process that achieves a specific form by pouring molten metal into a mold and allowing it to cool, without the application of mechanical force. This technique has been used for thousands of years, from the ancient lost wax method to modern die casting.
Cutting processes fall into three major categories: chip producing processes, burning, and miscellaneous specialty processes. Chip producing processes involve the use of tools to remove material in the form of chips or swarf, while burning processes use heat to separate pieces of metal.