There is nothing outwardly remarkable about the ore pitchblende. Samples of it are available in university geology laboratories, where they might be inspected by students or borrowed by school girls masquerading as Marie Curie at science fairs. Pitchblende is brown, gray, and black, with a lustre described in technical manuals as ‘greasy’, and it sometimes appears in clusters that resemble grapes on a vine. Madame Curie, who got her samples of pitchblende from Europe’s geological museums, discovered that the ore held small amounts of radium, which interested and delighted her; she and her husband, Pierre, filled test tubes with radium to show captivated visitors, and Marie kept a glassful of the stuff next to her bed for illumination. Pitchblende is the most common form of the mineral uraninite, which holds traces of radium, thorium, and polonium but is principally constituted of uranium oxide. It yields abundant uranium.
The source of Curie’s museum pitchblende, and before the First World War the only known source of uranium anywhere, was Joachimsthal (or Jachymov) in northwestern Bohemia, then part of Austria-Hungary. The area, known as the Erzgebirge, is wooded and mountainous. It was first known for its silver, discovered there early in the sixteenth century and formed into coins by the local count. He called the coins ‘Joachimsthalers’, later contracted to ‘thalers’ and then ‘dollars’ in English. The silver ore appeared in the upper workings of the mine; cobalt, nickel, and bismuth came further down; at the lowest level, embedded in narrow veins that ran through dolomite and quartz, was pitchblende. The Renaissance scientist Georgius Agricola came to Joachimsthal to study the region’s minerals, to write the first serious book that classified minerals according to their properties, and to invest enough in the Gotsgaab (God’s Gift) mine to keep his family comfortable for the rest of his life. The German chemist Martin Heinrich Klaproth was the first, in 1789, to derive a grey metal from Joachimsthal pitchblende. He called it uranium, after the recently discovered planet Uranus. Ceramicists found uranium a useful coloring substance for their glazes, for it imparted a yellow, orange, or brown color to the vessels they made. Early in the twentieth century, Joachimsthal and its surrounding area became a destination for Europe’s rich, seeking out the nourishing radioactive waters at Carlsbad, Marienbad, and Jachymov itself, site of the world’s first radon spa. A precocious American student named J. Robert Oppenheimer would later write his prep school thesis on the ores of Joachimsthal.1
After the First World War Joachimsthal uranium slipped from prominence—several recently found sites were richer—but with the discovery of uranium fission by Otto Hahn and Fritz Strassmann in late 1938 the Czech deposits assumed enormous strategic importance. The Erzgebirge was part of the Sudetenland, given to Hitler following the Munich Conference in September 1938. The German War Office learned in April 1939, a month after the German occupation, in violation of Munich, of all Czechoslovakia, that a nuclear weapon might be feasible. The physical chemist Paul Harteck and his colleague Wilhelm Groth wrote to military officials that ‘the newest development in nuclear physics... will probably make it possible to produce an explosive many orders of magnitude more powerful than conventional ones’. The War Office gave the Berlin-based Auer Company a contract for refining Joachimsthal’s uranium. The director of Auer’s laboratory, Nikolaus Riehl, had been a student of Hahn and Lise Meitner in Berlin. Thereafter, Professor Abraham Esau took charge of the project (though ‘project’ is perhaps too grand a term to describe it at this stage). By early the following year a good deal of Joachimsthal’s uranium was arriving at the War Office. German officials decided that spring to prohibit export of uranium compounds.2
The uranium at Joachimsthal gave the Germans a head start on their nuclear reactor, or burner, a machine needed to initiate controlled nuclear chain reactions. But the ore dug from the Erzgebirge was neither as abundant nor as pure as that found near the village of Shinkolobwe, in southern Katanga province of the Belgian Congo. Local people had mined the area for copper long before the Europeans arrived. In 1915 a Briton named Robert R. Sharp came upon a ridge that rose 35 feet above the Katangan countryside. It was speckled with green, yellow, and orange minerals— copper, presumably, in the first instance, but something very different in the second and third. Underneath the topsoil Sharp found a large vein of pitch-blende. A bit of digging revealed an extensive web of pitchblende and a colorful variety of other uranium minerals, in shades of yellow and orange. At Sharp’s prodding, the Belgians opened a mine on the Shinkolobwe outcrop in 1921.
The Belgian firm Union Minière du Haut-Katanga took charge of mining at Shinkolobwe. No one was yet interested in the uranium compound of pitchblende, but geologists knew that, where there was uranium, there was also radium, Marie Curie’s experimental interest and a substance with commercial appeal: manufacturers of wrist watches painted it on timepiece dials to make them glow in the dark, and some scientists hoped it might be used to treat cancer. Hidden away in three tons of uranium was a single gram of radium, 20,000 times more precious than gold. Union Miniere hired 200 local Bayeke men to work the mine. Four white company officials gave the orders and handed the Bayeke picks and shovels. The men chopped at the earth, dislodging heavy chunks of the yellow ore, which they placed in cloth sacks. Full sacks went by buffalo cart to the railhead at Kambove, next in British-built train cars to Lobito on the West African coast, and then by ship to Antwerp. Over time, steel drums replaced the inefficient sacks. And the miners went deeper into the earth, revealing ever-richer deposits of uranium and its more exalted constituent. From Antwerp the ore was sent to a newly constructed refinery in the town of Oolen, which processed out of it minute portions of radium. Marie Curie was made a consultant to the process. The radium was carefully encased in lead and sent under guard to hospitals and labs throughout Europe. The spent uranium was dumped in piles outside town, where, as Martin Lynch has written, ‘the yellowish waste was left to soak up the rain’. There the piles sat, and grew, for nearly two decades.4