A search turned up this example of cocaine being diluted with marble powder:
> High concentrations of Al, Ca, Fe, Mg, Mn, and P were found, indicating that adulterants such as gypsum, marble powder, limestone, cement, and others must be used to increase the profitability of the illicit drug market.
Diluting a very expensive product with something very cheap and selling it for the price of the pure product would certainly be a way of increasing profits.
From what I've read, many overdoses happen when users who are used to diluted heroin get hold of pure heroin, ending up with a much bigger dose than expected.
The paper I cited notes another risk for cocaine users: "Diluting substances such as talc, plaster, lime and chalk, used to increase the volume of the drug, are not absorbed and can cause chronic obstructive pulmonary diseases, such as silicosis".
I have never seen coke cut up with those substances. Mannitol is mainly used in Europe. To test cocaine on how pure it is many people test it by checking how much solves in water.
That's why people take prescription opiates - it says right on the tin how much it is. With the street stuff you have to estimate the purity, even the compound, there's dozens of opiates, and sometimes people get it wrong.
In Russia (Saint Petersburg) two amateur drug dealers were charged for police murder because they didn't know they should dilute their shit, and a policeman died after using the seized goods, because they were too pure.
> heroin would be diluted with more than five tons of marble dust from a quarry on nearby Mount Pentelikon
heroin diluted with marble? it this real?