As far as I remember, the whole thing was purely political. The silver price went up, because of monopoly reasons. At that time, I calculated the difference in price for a certain pack of B&W paper. It was say: 1 penny. But they charged one dollar more. The price for hydrochon went up too. The reason: the price of of silver was up! That is the logic behind it.
Jed
More specifically, they attempted to create a cartel. It failed.
Today, the conditions for forming a silver cartel are far more favorable.
30 years ago, most silver came from four sources
1) True silver ores (usually with lots of Antimony)
2) Parkes Process refining of Lead
3) Electrolytic processing of Copper ores
4) Recycling of silver from the photographic process (mostly the production of materials)
4 bears mention. Fully 85% (!) of the silver used in photographic processing is recycled as scrap. No doubt that figure has increased over the years.
Here's where we are now...
1) There's very little silver, silver/antimony ore left that's easy to come by. Nobody is going to hit another "Comstock Lode" anytime soon.
2) The industrial use of Lead has been curtailed and the Parkes Process is somewhat out of favor
3) Most silver is produced as a result of electrolytic processing of Copper ores. This is the main source today.
4) Less silver is being recycled from photographic processes since less of these materials are being produced
Not a lot of people realize this, but until about the early 1890s (or thereabouts) the ratio of gold to silver prices was about 15:1 in the USA because of the possiblity that the dollar would be backed by silver instead of gold. When that ceased to be a possibility, the ratio moved to 50:1 and silver prices crashed. I've never bothered to research it, but I wouldn't be surprised to learn that this drop helped spur the viability of photography for the general public in the early decades of the 20th century.
Now we've got the real possiblity that central banks (e.g. India) will be holding vast amounts of silver as a hedge against a declining dollar. As a result, many feel that the gold:silver price ratio will start to drop and silver will become considerably more expensive. Plus silver has always been pretty popular for jewelry in parts of the world where economic growth is particularly high at the moment (China, India) and this increases physical demand.
If those brothers tried to form a cartel in 2007 they may have met with more long-term success. They would also be aided by the fact that there's been a huge wave of mergers and acquisitions of copper mining outfits recently.
Not a pleasant thought...but as I type this I see that silver is back up to around $14.25 / troy ounce.