Nephrite as a surface treatment. A lot of nephrite tools and amulets are known since the Early Neolithic (VII mill. BC) to the Late Chalcolithic (V mill. BC) on the Balkans (mainly Bulgaria; also in Greece, Serbia, Croatia) from two or more unknown sources - Balkan "nephrite culture". Such tools are found in the Later Neolithic of Poland (from the most probable local source Jordanów), Sardinia (Italy) (unknown source) and Switzerland (Kostov, 2005; 2013). Single or just a few finds of nephrite artifacts are reported also from some other European countries. During Neolithic times, the key known sources of nephrite jade
Rock concert Rock concert A rock concert is a musical performance in the style of any one of many genres inspired by "rock and roll" music. While a variety of vocal and instrumental styles can constitute a rock concert, this phenomenon is typically characterized by bands playing at least one electric guitar, an electric bass guitar, and drums. Often, two guitar players share the tasks of rhythm and lead guitar playing. Rock concerts also have a social history which shapes the perception of the linguistic term and the activity itself. During the 1950s, several American musical groups experimented with new musical forms