How ancient people used to identify pure gold

Touchstone is a solid black stone with a streak of gold on it to show the purity of the gold. The mineralogical name is Bi Xuanite, also known as flint slate, siliceous slate, etc. It is a basaltic extrusive rock, dense, hard, and black. As an ornamental stone, it is best to have a dark body, and if there is a gold thread like a hairspring on it, it is a top grade.

"The Oldest Gold of Mankind" was found in the Varna Necropolis, on the Bulgarian Black Sea Coast. The Varna Necropolis, also known as Varna Cemetery, is a large burial site located in the western industrial zone of Varna. It is internationally recognized as one of the most significant archaeological sites in world prehistory. At this site, archaeologists discovered the oldest worked gold treasure in the world, dating from 4,600 BC to 4,200 BC. A total of 294 graves, dating between 4569-4340 BC, have been uncovered at the Varna Necropolis so far, containing around three thousand gold artifacts. Among the numerous elite burials, one burial in particular stood out - grave 43. In this grave, archaeologists unearthed the remains of a high-status male who appeared to have held a position of leadership or rulership. The amount of gold discovered within this burial exceeded the quantity found in the entire rest of the world during that period.

The whole “Connections” series was great

This gold Persian dagger belongs to the Achaemenid Era, c. 550-330 BC. On both sides, representations of a lion and a ram can be seen, symbolizing the Persian empire. The Achaemenid Persian empire stood as the largest in the ancient world, spanning from Anatolia and Egypt across western Asia to northern India and Central Asia. Its origins trace back to 550 B.C., when King Astyages of Media, who held dominion over much of Iran and eastern Anatolia (Turkey), was defeated by his southern neighbor Cyrus II ("the Great"), the king of Persia (r. 559-530 B.C.).

The color of the gold powder left by gold scratched on the touchstone is called streak in mineralogy, and it is also a commonly used method in modern mineralogy to distinguish minerals by the color of the mineral end (stripe). Gold is soft and easily scratches. The darker the color of the touchstone, the smoother and flatter it will be, and the clearer the streaks will be.

All the gold ever mined would fit into a cube with just 22 meters on each side. Thousands of years ago people found they could verify gold's purity by rubbing it against a certain kind of rock (called a touchstone) and checking the color of the streak it made.

Botswana President reacts to discovery of world's second largest diamond weighing 2,492 carats. 😂

I prefer Archimedes’ method

I have another question: how did humans came to the idea that gold is worth more than other metals?

Who is this guy? I remember this show but don't remember its name.