A bifacial tool knapping industry existed at the site where axes and adzes characteristic of the Neolithic and Chalcolithic periods were produced. The tools were knapped from larnite (Ca2SiO4)—a dense metamorphic rock that is c. 20% heavier than flint, with a chemical composition that resembles Portland cement. The Hatrutim Formation is the only geological formation in the Levant where larnite appears. A light gray patina covers the rock and obscures it texture and its black color.

Despite the proximity of natural flint sources suitable for knapping bifacials, there is evidence of widespread utilization of larnite in the Hatrutim Quarry. There is extensive evidence of mining at the site, including extracted larnite nodules and the negatives of larnite nodules that were extracted for the purpose of knapping.
A large concentration of chipping debris and numerous tools discarded at different stages of the knapping process are prominent on the mountainside (2,900 sq m; Fig. 2). Shallow concentrations of waste production were also found along the top of the ridge (Fig. 3). The excavation focused on the region in the middle of the debitage dump (4 sq m; Fig. 4). Its purpose was to study the distribution of the waste types and to assess the thickness of the debitage dump. It was ascertained that the debitage stratum in the excavated region is c. 80 cm deep. At the bottom of the probe was a rock shelf made of large larnite nodules (Fig. 5). Hundreds of scattered debitage items—a byproduct of knapping the axes and adzes—were found (Fig. 6). Apart from tools discarded during the knapping process and collected from the surface, three tools, not completely fashioned, were recovered from the excavation itself. One of the tools is apparently a large adze that was found broken in two parts (Fig. 7).
The chipping debris and tools in the excavation weigh c. 209 kg. Identical chiseling was found on two flakes; it is probably a result of the quarrying activity and removal of the cortex of the nodules prior to knapping (Fig. 8). An examination of the bifacial tools that were taken for further documentation in the laboratory shows that most of them have a flat-convex cross-section, indicating they were meant to be turned into adzes—the most common tools in the late Pottery Neolithic and Chalcolithic periods.
Another site, where a similar scale trial excavation (Licenses Nos. G-71/2010, G-20/2011) was conducted, had previously been discovered deep in the Hatrurim Valley, inside the Southern Judean Desert Nature Reserve. Finds identical to those documented in the Hatrurim Quarry were discovered at that site, including extensive evidence of quarrying raw material, as well as large amounts of chipping debris that consisted of axes and adzes in various stages of production (http://antiquity.ac.uk/projgall/vardi332/).
Knapping sites of bifacial tools are known from a variety of places throughout the world; in many, the knapping region is close to the source of raw material. A production site of the basalt bi-facial tools was discovered several years ago at Giv‘at Kipod in the area of the Carmel (Rosenberg, Shimelmitz and Nativ 2008). Until recently no quarrying and knapping sites of bifacial tools were known in the south of Israel, and certainly not of larnite. The scope of the finds at the Hatrurtim site, including hundreds of unfinished tools that were found on the surface, shows that the site was active for an extended period; however, in the absence of any indicative finds or organic material that can be radiometrically dated, a more precise dating of the range of activity at the site will only be possible if larnite tools will be discovered in lithic assemblages at other sites.