Galena is a lead sulfide mineral with a chemical composition of PbS. It is one of the earliest minerals used by humans. It is also an ore of lead metal and is mined from a large number of deposits in many countries.
Galena mineral is often associated with sphalerite, calcite, and pyrite. Silver is its most common compound, followed by copper and zinc, sometimes containing iron, arsenic, bismuth, etc.
- Galena meaning: Named by Pliny the Elder in 77-79 from the Greek "galene" meaning "lead ore".
- Chemical composition: Lead sulfide, PbS
- Galena hardness: 2.5 on Mohs scale
- Lead color: Lead-grey
- Galena luster: Metallic, Dull
- Galena streak: Lead gray to black
- Galena cleavage: Perfect, cubic, three directions at right angles
- Morphology: Galena cubes, octahedrons, cube-octahedron combinations and rarely dodecahedrons.
- Specific gravity: 7.4 - 7.6
- Galena crystal System: Isometric
- Galena mineral group: Galena group
How is galena formed?
Galena is found in igneous and metamorphic rocks in medium or low-temperature hydrothermal veins. In sedimentary rocks, it occurs as veins, breccia cement, isolated grains and as replacements of limestone and dolostone.
Some galena mines contain up to 0.5% silver, a byproduct that far surpasses the main lead ore in revenue. This argentiferous galena almost entirely of hydrothermal origin is the ore of silver. Galena in lead-zinc deposits contains little silver.
Galena is also often mixed with copper. After weathering, it becomes white lead ore and Lead alum.
Who produces galena？
The world's largest galena deposit is the State of Missouri, USA, with 30 million tons of lead reserves. Yunnan Jinding and Qinghai Xitiesha (China), Cornwall (UK), Freiberg (Germany) and Broken Hill (Australia) are also galena producers.
Currently, about 240 mines in more than 40 countries produce lead. The world’s annual lead production exceeds 10 million tons, mainly in countries such as Australia, China, the United States, Mexico, Sweden, Peru, Russia, Canada, and Morocco. About half of them are obtained through recycling waste.
Old history of galena
Galena has been used throughout ancient times for different reasons, but it's mainly used for smelting.
- One of the earliest galena uses was as kohl. The Ancient Egyptians used galena powders to rub around their eyes to reduce the glare of desert sun and repel flies;
- In ancient Rome, people gave it this academic name. They smelted down galena ore to make water pipes and public baths;
- The Ancient Babylonian and Assyrian people used galena as a construction material;
- Chinese empires used galena to make coins as the currency;
- After the invention of cement movable type printing in the Northern Song Dynasty, the Germans used galena to invent alloy movable type printing;
- In the war, people used galena to make weapons. Lead paint can remove the barnacles attached to the bottom of ship to protect the ship from breaking through the waves;
- In the early days of wireless, galena crystal was used as the semiconductor in crystal radios. It became part of a point-contact diode used to detect radio signals.
After processing of galena rock, lead is widely applied in making batteries, alloys, ceramic, stained glass, sheets, paint, pipes, cosmetics, etc. Lead is the world's claimed industrial metal and the demand for it outstrips the supply.
1. Lead-acid batteries
Most lead is consumed in making batteries. In America, 80% of lead is used in automotive-type, lead-acid batteries. A battery contains twenty pounds of lead and must be replaced every 4-5 years.
The batteries are also used as standby power supplies for computer networks and communication facilities.
2. Radiation shielding
Lead can absorb X-rays, making radiation difficult to pass through. Thus it is used as a protective wall for radiation, such as a device for storing nuclear waste. It can effectively prevent nuclear leakage.
The screen of electronics, such as computers, TV and cellphones, use lead to protect us from radiation and enhances the image.
X-rays and imaging diagnostics (CAT scans) use sophisticated lead shielding to protect patients and healthcare professionals. Special lead-lined rooms are made for life-saving radiation treatments.
3. Galena pottery
One of the world's finest pottery is the galena pottery. It is glazed with lead, including the official White House dinnerware in many administrations.
4. Stained glass
Stained glass pieces of cathedral windows are held together by malleable lead cames, which can be relied on to endure for centuries. Many colors were created with lead and the finest stemware is made from lead crystal.
5. Measurement instrument
Due to the good ductility and toughness, lead is used for making the measurement instrument plumb in construction. Some words such as "plumbing"，"plumber", "plumb", and "plumb-bob", their roots are derived from the Latin "plumbum" (lead).
Is lead very dangerous？
Lead has a negative effect on human life and production. Excessive lead dust causes plumbism, which is harmful for human organs and tissues like heart, bones, intestines, kidneys, reproduction and nervous system.
Therefore, please avoid inhaling dust when crushing and wash hands after handling. In the iron ore provided for smelting, if lead exceeds the allowable content requirement, the furnace lining will be damaged and the furnace life will be shortened.
Many uses of lead and lead compounds (ceramic, cosmetics, glass, etc.) have been discontinued or significantly reduced over the past few decades in response to health concerns. Many schools removed galena from student mineral kits and replace it with a mineral with a lower level of concern.