# Experimental Simulation of Lightning Current Discharge on Rocks
## 5 Conclusions  
The randomness in time and space of lightning occurrences makes direct measurement of lightning difficult and consequently makes the studies on lightning processes generating rock fulgurite challenging. This paper reports the first attempt to measure the electrical conditions required to form a rock fulgurite. The data reported in this study provides a means of directly determining energy, voltage, current, and peak instantaneous power as parameters of an event mimicking the effect of the lightning current discharges hitting the surface of the rock and passing to ground.  
The textural features and electrical properties of basalt (samples A1-A4) reported in this paper showed that the series of events occurred to produce a rock fulgurite can be summarized as follow: (i) ultrafast mechanical impact of the leader spark with the rock surface. Consequently, a crater appears and an increase of pressure occurs around the hole; (ii) the sudden rise of temperature generated by the lightning channel melting of the rock; and (iii) fast cooling and generation of the glass (fulgurite) in the rock. Further investigations on the microstructure and texture of these samples will be carried out in future experiments in order to investigate the physical properties and thermal effects resulting from electrical arc discharge through a target material.  
The methods presented it this paper are accessible to a wide range of researchers studying the interaction of electrical discharges and rocks. In particular, methods for extracting fault onset and extinction times from time-series measurements taken with common electronic laboratory equipment have been described. These calculations enable power and energy estimations, which can be used to better understand how electric discharge properties relate to rock fulgurite properties in a quantifiable manner.  
Technical applications related to lightning effects on materials may potentially benefit from the results reported in this paper. Recognizing the paths that lightning can take through a material and the reactions occurring after a lightning impact are essential for mitigating thermal damage from lightning strikes and understanding the nature of the lightning environment near and at the point of a direct strike. Moreover, understanding how target materials interact with electrical arcs can support the development and testing of materials used in hazard protection devices such as lightning arresters and high-voltage fuses.  
Conceptualization, C.E., N.S.C., and E.S.; Data curation, C.E., N.S.C., and K.M.; Investigation, C.E. and N.S.C.; Methodology, C.E., N.S.C., and E.S.; Supervision, C.E. and K.M.; Validation, C.E. and K.M.; Writing--original draft, C.E. and N.S.C.; Writing--review and editing, C.E., N.S.C., K.M., and E.S.  
This research received no external funding.  
**Acknowledgments:** Authors would like to thank [PERSON] for his technical support and thoughtful advice in designing the experimental apparatus at Drexel University's Center for Electric Power Engineering (CEPE). Three anonymous reviewers are acknowledged for their comments that greatly improved the manuscript.  
**Conflicts of Interest:** The authors declare no conflict of interest.