**6. Discussion and Conclusions**

These four examples of obsidian studies in the central Mediterranean illustrate the importance of analyzing large numbers of artifacts, allowing statistically significant numbers for comparisons based on variables, including time period, open-water distance, visual and physical properties, and cultural contexts. One overall accomplishment is the documentation of long-distance travel routes, based on the distribution proportions and quantity of obsidian artifacts from the different geological sources (Figure 15). This involved minimizing open-water travel when possible, while demonstrating multiple steps and the likely multiple transactions during the Neolithic, prior to the development of both complex societies and technological advancements in the Bronze Age, leading also to the decreased long-distance distribution of obsidian. In general, there was a major long-distance distribution to the north and northwest, which began with the spread of agriculture and domesticated animals in the Early Neolithic and continued through the end of the Late Neolithic (ca. 6000–3000 BCE) [2,3,37].

Over the last decade, more than 75% of the elemental analyses of obsidian were accomplished with the development of non-destructive XRF instruments, especially those that are hand-held and easily portable, which have enabled low-cost and rapid analyses of archaeological artifacts within museums and storage facilities. This has changed the status of our research on obsidian, as described in the recent past [14]. Many other methods have shown to be quite successful in distinguishing geological sources, and there are still experimental studies continuing with a variety of analytical methods, including Cl and Na proportions, geological formation age, and magnetic properties. Most important, however, is still the need for further studies of excavated obsidian artifacts, for different time periods and geographic locations, and integration with studies of lithic typology, the technology

used for the production of stone tools, microscope-based use-wear patterns, and other parts of the *chaîne opératoire*.

**Figure 15.** Obsidian distribution directions in the central Mediterranean.

**Funding:** Travel costs for this research have been partly funded by the University of South Florida.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Elemental data for individual artifacts is published or in course of publication. Requests may be sent to the author.

**Acknowledgments:** The extensive use of the pXRF would not have been possible without the consent of many colleagues and permissions obtained from many museums and government superintendencies in Sicily, peninsular Italy, Croatia, and Malta. I thank Andrea Vianello for assistance with this, as well as with the use of the pXRF in Italy. I also thank Kyle Freund for assistance in conducting analyses in Sicily and Southern Italy. The pXRF instruments were acquired by the author.

**Conflicts of Interest:** The author declares no conflict of interest.

#### **References**

