1. Introduction
The Ga’ara ironstone occurs in the upper part of the Ga’ara
Formation which is exposed in the Ga’ara Depression, some
65 km to the north of Rutba town in the Western Desert of Iraq.
It lays between latitudes 33_2500000–33_4000000N and longitudes
40_0300000–40_3800000E (Fig. 1). Outcrops of these ironstone occurrences
were found in more than nine hillsides along the southern
border of the Ga’ara Depression which extends for _60 km in the
east–west direction and has a width of _30 km. The ironstones
were discovered in the 1960s and investigated at that time by
Vasiliev et al. (1964). Several investigations followed subsequently,
including the Techno-export (1965), Chaikin (1970), Yakta (1972,
1981), Lange (1975) and Tobia (1983). Another ironstone of
Jurassic age occurs to the southeast of Ga’ara Depression that has
some similarities and differences with the studied Ga’ara
 ironstones; this occurrence is the Hussainiyat ironstone that was
studied by Al-Bassam and Tamar-Agha (1998).
The detailed petrographical and geochemical evidences and
genesis of the Ga’ara ironstone are the matter of this article. Comparison
with the Hussainiyat ironstone will also be discussed.