Galena                        Mineral Group: SULFIDES
aka Lead

  • Galena is a very heavy mineral that grows cubic crystals.
  • The crystals can also be dodecahedral in shape.
  • It is known as lead.

 

Galena crystals    from Picher, Oklahoma   USA

   


galena w/ ruby sphalerite  Picher, Oklahoma USA

 

Galena crystals in Dolostone   from Lafarge Quarry, Dundas, Ontario CANADA

    

 

Galena – Mother of Lead
© Bert Ellison 1999 - 2002

As collectors of minerals, one of the most sought–after specimens on trips to mine dumps is surely fine galena cubes. Although galena may show up in several other forms, the isometric cubic habit is the most cherished, with sides up to eight and ten centimetres. Seldom a single trophy, the brilliant cubes are usually twinned into clusters, making for a great cabinet display.

Galena (PbS) is the most common ore of the metal, with 87 percent lead and 13 percent sulfur, but it is usually host to valuable amounts of sulfur and gold as well as possible selenium, zinc, cadmium, antimony and copper sulfides. It is frequently found with zinc (sphalerite ZnS) and silver ores. One book lists over 150 other minerals containing lead.

The symbol Pb stands for plumbum, the Latin name for lead, so it was logical at the time to call those who worked with it "plumbers". And so it is. Field tests, aside from the nice cubic habitat are: H 2.5 (soft) and SG 7.6 (heavy) and a grey streak on test tiles. It’s one of the most widely distributed of the metallic sulfides and, not surprisingly, a good candidate for ancient "metallurgists". Lead relics predate Egyptian times and the role of lead in Roman history is legendary, from lead utensils (wine goblets!) to lead pipes. It’s reckoned that any resourceful civilization would – sooner or later – learn that a fire next to a suitable outcrop would liquefy galena to the metal. Modern metallurgy has learned to handle the more common, complex ores.

Lead has many uses both modern and ancient. Roman pipes still pour water into the baths at, yes, Bath, England.

Sheet lead was widely used (still is) for Church roofing in the Middle Ages where it had another handy use – melted and poured onto attacking invaders it must have been a spectacular deterrent.

These days we no longer pour it onto heads but into things like battery plates – the largest user by far – solder, type metal, low-fusing alloys with bismuth and tin, engine bearings, pigments (but not in household paints), as azide in detonators and shielding (as glass) in x-ray rooms and around atomic reactors. And for fun make a simple radio receiver using a galena crystal. Parts should be found at radio supply shops.

We are now more sensitive to dangers in many ways and lead compounds are high on the list. It has serious consequences to the brain especially in children. Tetraethyl of lead for decades put in gasoline to reduce engine knock is gone. It’s no longer in domestic paints or glaze on pottery. Even the solder (lead and tin alloy) used with copper piping is suspect. Lead shot kills birds which ingest it instead of natural grit for the gizzards. The sweetish taste of lead paint tempted children to nibble peeling bits. It’s now known that the ill-fated Franklin Arctic expedition of 1845 may have been handicapped from lead poisoning from soldered food tins.

These depressing observations indicate not only the hazards but how ubiquitous is this valuable metal in our society.

And, despite the joke, dear readers, lead is not used to make balloons!

 

Galena and Quartz on Marcasite  from  Casteel #35 Mine, Viburnum, Missouri, Iron County, USA

   

 

Galena  from Sweetwater Mine, The Lead Pillar Room 1,300 ft. level, Doe Run Mine, ASARCO Inc., Reynolds County, Missouri  USA

   

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