Platinum was often found with two other metals, iridium and osmium, which were even denser, harder, more refractory. Here Uncle pulled out samples for me to handle, mere flakes, no larger than lentils, but astoundingly heavy. They were ‘osmiridium’, a natural alloy of osmium and iridium, the two densest substances in the world. There was something about heaviness, density – I could not say why – that gave me a thrill, and an immense sense of security and comfort. Osmium, moreover, had the highest melting point of all the platinum metals, Uncle Dave said, so at one time it was used, despite its rarity and cost, to replace the platinum filaments in lightbulbs.
The great virtue of the platinum metals was that while they were as noble and workable as gold, they had much higher melting points, and this made them ideal for chemical apparatus. Crucibles made of platinum could withstand the hottest temperatures; beakers and spatulas of it could withstand the most corrosive acids. Uncle Dave pulled out a small crucible from the cabinet, beautifully smooth and shiny. It looked new.
‘This was made around 1840’, he said. ‘A century of use, and almost no wear.’
My grandfather’s oldest son, Jack, was fourteen years old in 1867, when diamonds were found near Kimberley in South Africa and the great diamond rush began. In the 1870s Jack, along with two brothers – Charlie and Henry (Henry was born deaf and used sign language) – went to make their lives and fortunes in South Africa as consultants in the diamond, uranium, and gold mines (their sister Rose accompanied them). In 1873 my grandfather remarried, and had thirteen more children, and the old family myths – a combination perhaps of his elder sons’ stories, Rider Haggard’s tales of King Solomon’s Mines and the old legends of the Valley of Diamonds – caused two of the next-born (Sydney and Abe) to join their half-brothers in Africa. Later still, two of the younger brothers, Dave and Mick, joined them as well, so at one point seven of the nine Landau brothers were working as mining consultants in Africa.
A photograph that hung in our house (and now hangs in mine) shows a family group taken in 1902 – Grandfather, bearded and patriarchal, his second wife, Chaya, and their thirteen children. My mother appears as a little girl of six or seven, and her youngest sister, Dooggie – the youngest of the eighteen – as a ball of fluff on the ground. The images of Abe and Sydney, one can see if one looks closely, have been grafted into place (the photographer had arranged the others to make spaces for them), for they were still in South Africa at the time – detained, and perhaps endangered, by the Boer War.[2]
The elder half-brothers, married and rooted now, stayed in South Africa. They never returned to England, though tales of them constantly circulated in the family, tales heightened to the legendary by the family mythopoeia. But the younger brothers – Sydney, Abe, Mick, and Dave – returned to England when the First World War broke out, armed with exotic tales and trophies of their mining days, including minerals of all sorts.
Uncle Dave loved handling the metals and minerals in his cabinet, allowing me to handle them, expatiating on their wonders. He saw the whole earth, I think, as a gigantic natural laboratory, where heat and pressure caused not only vast geologic movements, but innumerable chemical miracles too. ‘Look at these diamonds’, he would say, showing me a specimen from the famous Kimberley mine. ‘They are almost as old as the earth. They were formed thousands of millions of years ago, deep in the earth, under unimaginable pressures. Then they were brought to the surface in this kimberlite, tracking hundreds of miles from the earth’s mantle, and then through the crust, very, very slowly, till they finally reached the surface. We may never see the interior of the earth directly, but this kimberlite and its diamonds are a sample of what it is like. People have tried to manufacture diamonds’, he added, ‘but we cannot match the temperatures and pressures that are necessary.’[3]
On one visit. Uncle Dave showed me a large bar of aluminium. After the dense platinum metals, I was amazed at how light it was, scarcely heavier than a piece of wood. ‘I’ll show you something interesting’, he said. He took a smaller lump of aluminium, with a smooth, shiny surface, and smeared it with mercury. All of a sudden – it was like some terrible disease – the surface broke down, and a white substance like a fungus rapidly grew out of it, until it was a quarter of an inch high, then half an inch high, and it kept growing and growing until the aluminium was completely eaten up. ‘You’ve seen iron rust – oxidizing, combining with the oxygen in the air’, Uncle said. ‘But here, with the aluminium, it’s a million times faster. That big bar is still quite shiny, because it’s covered by a fine layer of oxide, and that protects it from further change. But rubbing it with mercury destroys the surface layer, so then the aluminium has no protection, and it combines with the oxygen in seconds.’
I found this magical, astounding, but also a little frightening – to see a bright and shiny metal reduced so quickly to a crumbling mass of oxide. It made me think of a curse or a spell, the sort of disintegration I sometimes saw in my dreams. It made me think of mercury as evil, as a destroyer of metals. Would it do this to every sort of metal?
‘Don’t worry’, Uncle answered, ‘the metals we use here, they’re perfectly safe. If I put this little bar of tungsten in the mercury, it would not be affected at all. If I put it away for a million years, it would be just as bright and shiny as it is now.’ The tungsten, at least, was stable in a precarious world.
‘You’ve seen’, Uncle Dave went on, ‘that when the surface layer is broken, the aluminium combines very rapidly with oxygen in the air to form this white oxide, which is called alumina. It is similar with iron as it rusts; rust is an iron oxide. Some metals are so avid for oxygen that they will combine with it, tarnishing, forming an oxide, the moment they are exposed to the air. Some will even pull the oxygen out of water, so one has to keep them in a sealed tube or under oil.’ Uncle showed me some chunks of metal with a whitish surface, in a bottle of oil. He fished out a chunk and cut it with his penknife. I was amazed at how soft it was; I had never seen a metal cut like this. The cut surface had a brilliant, silvery luster. This was calcium, Uncle said, and it was so active that it never occurred in nature as the pure metal, but only as compounds or minerals from which it had to be extracted. The white cliffs of Dover, he said, were chalk; others were made of limestone – these were different forms of calcium carbonate, a major component in the crust of the earth. The calcium metal, as we spoke, had oxidized completely, its bright surface now a dull, chalky white. ‘It’s turning into lime’, Uncle said, ‘calcium oxide.’
But sooner or later Uncle’s soliloquies and demonstrations before the cabinet all returned to his metal. ‘Tungsten’, he said. ‘No one realized at first how perfect a metal it was. It has the highest melting point of any metal, it is tougher than steel, and it keeps its strength at high temperatures – an ideal metal!’
Uncle had a variety of tungsten bars and ingots in his office. Some he used as paperweights, but others had no discernible function whatever, except to give pleasure to their owner and maker. And indeed, by comparison, steel bars and even lead felt light and somehow porous, tenuous. ‘These lumps of tungsten have an extraordinary concentration of mass’, he would say. ‘They would be deadly as weapons – far deadlier than lead.’
2
There were fears for all the African relatives during the Boer War, and this must have impressed my mother deeply, for more than forty years later, she would still sing or incant a little ditty from this era:
One, two, three – relief of Kimberley
Four, five, six – relief of Ladysmith
Seven, eight, nine – relief of Bloemfontein
3
There were many attempts to manufacture diamonds in the nineteenth century, the most famous being those of Henri Moissan, the French chemist who first isolated fluorine and invented the electrical furnace. Whether Moissan actually got any diamonds is doubtful – the tiny, hard crystals he took for diamond were probably silicon carbide (which is now called moissanite). The atmosphere of this early diamond-making, with its excitements, its dangers, its wild ambitions, is vividly conveyed in H.G. Wells’s story ‘The Diamond Maker.’