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Realgar

earth science Maturity 7-9 Next article →

Realgar is a bright mineral with a striking orange-red color. It is a type of arsenic sulfide mineral. You might see it in crystal shapes. It can also look like a fine powder or small grains. Some people call it ruby sulfur or ruby of arsenic. This mineral is quite soft to the touch. It is often found near another mineral called orpiment.

This mineral forms in very specific ways. It often grows in low-temperature hydrothermal veins. These are cracks in rocks filled with hot water. It also forms near volcanoes. You can find it in deposits from hot springs. Realgar is often found with other minerals. These include calcite, barite, and arsenolite. It sometimes appears near ores of lead, silver, and gold.

Humans have used realgar for many centuries. The name comes from an Arabic phrase. It means "powder of the mine." The first English records appear in the 1390s. In China, the name is Xionghuang. This name means "masculine yellow." In the Roman Empire, people traded realgar. They used it to make red paint. Artists in Egypt and India used it too. Venetian painters used it during the Renaissance.

Realgar has many different uses in history. Firework makers used it for white flames. It also helped make yellow smoke in daytime fireworks. People used it to kill weeds and pests. In medieval Spain, it was used to poison rats. In the 16th century, people in England used it for the same thing. Some doctors in Ancient Greece used it. They called a medicine made from it "bull's blood." This medicine was very dangerous.

Light can change how realgar looks. If it stays in the light for a long time, it changes. It turns into a yellow powder. This new powder is called pararealgar. People used to think this was just orpiment. Now we know it is a different chemical compound. Realgar is also found in the United States. You can find it in Mercur, Utah. It is also in Manhattan, Nevada. You can even find it in Yellowstone National Park.

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