Realgar

Realgar (riˈælgɑr,_-gər ), also known as "ruby sulphur" or "ruby of arsenic", is an arsenic sulfide mineral with the chemical formula α-. It is a soft, sectile mineral occurring in monoclinic crystals, or in granular, compact, or powdery form, often in association with the related mineral, orpiment (). It is orange-red in color, melts at 320 °C, and burns with a bluish flame releasing fumes of arsenic and sulfur. Realgar is soft with a Mohs hardness of 1.5 to 2 and has a specific gravity of 3.5. Its streak is orange colored. It is trimorphous with pararealgar and bonazziite. Its name comes from the Arabic rahj al-ġār (رهج الغار, "powder of the mine"), via Medieval Latin, and its earliest record in English is in the 1390s. Realgar is a minor ore of arsenic extracted in China, Peru, and the Philippines. Realgar was used by firework manufacturers to create the color white in fireworks prior to the availability of powdered metals such as aluminium, magnesium and titanium. It is still used in combination with potassium chlorate to make a contact explosive known as "red explosive" for some types of torpedoes and other novelty exploding fireworks branded as 'cracker balls', as well in the cores of some types of crackling stars. Realgar is toxic. It was sometimes used to kill weeds, insects, and rodents, even though more effective arsenic-based anti-pest agents are available such as cacodylic acid, , an organoarsenic compound used as herbicide and also to kill ants and mice. Realgar was commonly used in leather manufacturing to remove hair from animal pelts. Because it is a known carcinogen and an arsenic poison, and because substitutes are available, it is rarely used today for this purpose. The ancient Greeks, who called realgar σανδαράκη (), understood that it was poisonous. From this, realgar has also historically been known in English as sandarac. Realgar was also used by Ancient Greek apothecaries to make a medicine known as "bull's blood". The Greek physician Nicander described a death by "bull's blood", which matches the known effects of arsenic poisoning.