Our prehistoric ancestors were constantly looking for stone. As soon as ancient hominids started to use stone tools on a regular basis, some 2.6 million years ago and most probably even earlier than that, the search for their stone became second nature. Even the earliest African tool makers were highly familiar with the different outcrops available along the rift valley and made selective use of specific raw materials. This is actually the earliest example of a conceptual change in human–nature relationship, when people started looking at nature as a resource, as a supplier of their technological needs and demands.
Basalt is a common extrusive igneous rock formed from the rapid cooling liquid magma which has solidified after being ejected by erupting volcanoes. By definition, basalt must be an aphanitic igneous rock with less than 20% quartz and less than 10% feldspathoid by volume, and where at least 65% of the feldspar is in the form of plagioclase. Basalt is usually grey to black in colour, but rapidly weathers to brown or rust-red due to oxidation of its mafic (iron-rich) minerals into rust. Basalt, like Granite, is a very hard stone and almost always has a fine-grained mineral texture due to the molten rock cooling too quickly for large mineral crystals to grow. In general knapping artefacts from basalt is suggested to need more sophistication that making them from quartzite or chert. Early Paleolithic basalt artifacts are known mainly from Africa, the Near East and the Indian Subcontinent.
Basalt was used even from the earliest artifacts bearing sites. The Nachukui Formation is a geological deposit located on the western shore of Lake Turkana, northern Kenya, that includes archaeological sites dated to the earliest stone tool production in the world at c. 2.34 mya BP and even older. Raw materials in the Nachukui Formation consist of fine to coarse-grained volcanic rocks with large to nearly invisible embedded crystals. Four major rock types in the formation are phonolite, basalt, trachyte, and rhyolite.
Basalt chopping tools have also been reported from Bed I at Olduvai Gorge (http://www.britishmuseum.org/research.aspx?ref=header)
Basalt large cutting tools are known from the Middle Pleistocene of the Vaal river (South Africa). At the Pniel site, the hominids preferred volcanic, metamorphic and sedimentary rocks with preference of hornfels / basalt, while some andesite and trachyte as well as a few shale and quartzite specimens also occur. Cleavers are made selectively made from basalt while handaxes show no such preference.
Gesher Benot Ya’aqov (GBY) was excavated in the 1930s by Dorothy Garrod and Moshe Stekelis, and again in the 1960s by Isaac Gilead. Since 1989 excavations were conducted under the direction of Naama Goren-Inbar. The site is about 790 k.a. old. Nearly 13,000 stone artifacts have been recovered from GBY. The collection of artifacts is dominated by numerous Acheulean hand-axes, cleavers, cores, and flakes and flake tools. Many of the stone tools are made from local basalt. This raw material choice was used to argue for an African origin / tradition of the GBY hominids crossing the gates to Eurasia. Only a single cleaver and 39 handaxes at GBY were produced on flint.
Numerous basalt handaxes are known from Egypt (for example from Gilf Kebir). In the Maghreb and the Sahara, middle Pleistocene basalt bifaces and cleavers occurs, usually only in small quantities. The artifact displayed here is relatively small (9×4 cm) and flat (1,2 cm) and was found in the Lybian Sahara in the 1960 ies together with 25 other small (median: 6 cm) handaxes made selectively from Basalt.
The Indian subcontinents hundreds of Acheulean sites and scatters have been reported. Most are open-air sites, while a few occurrences have been reported from caves or rock shelters. Handaxes and cleavers made from basalt are well known from this area. Some atypical basalt handaxes are even known east from the “Movius line” derived from a series of Middle Pleistocene localities in the Imjin/Hantan River Basins in Korea.