Countries	Area	Samples	Activity concentrations (Bq/kg)			Ra_eq (Bq/kg)	References
Countries	Area	Samples	²²⁶Ra	²³²Th	⁴⁰K	Ra_eq (Bq/kg)	References
Yemen	Aden	Basalt	57.086	80. 2 6	846.21	236.04	Harb et al., 2014*
Iraq	Sidakan	Basalt	5.65	21.4	203.34	44.8	Ahmed and Hussein, 2011 [19]
Austria	Austria	Basalt	23.3	17.7	307.00	----	Sorantin and Steger, 1984 [20]
Sa. Arabia	Harrat	Basalt	07.90	09.14	234.81	36.57	Present work
Iran	Tehran	Granite	72.24	75.71	1126.28	272.32	Asgharizadeh et al., 2012 [21]
Sa. Arabia	Ryadh	Granite	9.94	0.25	359.74	50.05	Al-Saleh and Al-Berzan, 2007 [22]
Egypt	Aswan	Granite	14.94	15.50	370.23	35.73	El-Taher et al., 2007 [23]
Greece	Greece	Granite	64.56	85.53	1104.19	-----	Papastefanou et al., 2005 [24]
Sa. Arabia	Alquryyah	Granite	80.85	68.50	1376.69	284.81	Present work
Egypt	Sinai, Suez	Marble	56.78	5.95	142.8	76.29	Fares et al., 2011**
Sa. Arabia	Sa. Arabia	Marble	12.00	1.70	23.10	16.211	Al-Saleh and Al-Berzan, 2007***
Algeria	Product	Marble	23.00	18.00	310.00	73.00	Amrani and Tahtat, 2001****
Sa. Arabia	Madrekah	Marble	01.56	01.38	10.15	4.32	Present work