  Using high-resolution gamma-ray spectroscopy, the terrestrial gamma radiation
in all the predominant types of geological rock formations appearing in Cyprus
was measured. Soil samples were collected from each rock type, sealed in
1-litre plastic Marinelli beakers, and measured in the laboratory for 24 hours
each. From the measured gamma-ray spectra, activity concentrations were
determined for Th-232 (range from 1.3 to 52.8 Bq/kg), U-238 (from 0.9 to 90.3
Bq/kg) and K-40 (from 13 to 894 Bq/kg). Elemental concentrations mean values of
(2.8 +- 0.7) ppm, (1.3 +- 0.3) ppm and (0.6 +- 0.1) % were extracted, for
thorium, uranium and potassium, respectively. Absorbed dose rates in air
outdoors were calculated to be in the range of 0.1-50 nGy/h, depending on the
geological features, with an overall mean value of (14.7 +- 7.3) nGy/h. The
corresponding effective dose rates per person outdoors were estimated to be
between 0.1 and 61.4 microSv/y, assuming a 20% occupancy factor.
