Dosimetry is essentially how much radiation exposure you get from substances or machines that produce radiation. The science of dosimetry also deals with the effects that radiation has on the body.
Most mineral specimens produce radioactivity from .5-200 mR/hr ( milliRems per hour) measured at about 1/2 inch from the specimen. To put this in perspective take a look at the chart below which shows the radiation limits set by the government for people that work with radiation ( general public dose is about 1/5 of the worker rate)
Permissible occupational radiation dose levels are set by the chapter 10 part 20 of the Code of Federal Regulations (10 CFR 20).
Whole body dose limit for routine exposures = 5 rem/year.
Limits are based on the sum of internal and external exposure. When individual organs are exposed, the following limits apply (the whole body dose limit must still be met).
NOTICE THE RATE IS REMS NOT MILLIREMS! There are 1,000 milliRems in a Rem.
For the really gruesome facts here is an additional chart.
The effects of being exposed to large doses of radiation at one time (acute exposure) vary with the dose. Here are some examples:
What all this means is that you would need to hold a fairly hot (50 mR) radioactive mineral specimen in your hand for a total of 1000 hours just to reach the yearly, 50 Rem maximum for a radiation workers hands!
Check out this handy tool for calculating radiation dose from mineral specimens, ore and mine dump material.
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