Sulm (Austrian river) in the context of Leibnitz (district)

The Burgstallkogel (458 meters or 1563 feet; also known as Grillkogel) is a hill situated near the confluence of the Sulm and the Saggau river valleys in Southern Styria in Austria, about 30 km south of Graz between Gleinstätten and Kleinklein. The hill hosted a significant settlement of trans-regional importance from 800 BC to about 600 BC. Surrounding the hill is one of the largest Iron Age necropolises in continental Europe, originally composed of at least 2,000 tumuli.

The Koralpe (English: Kor Alps, German: [ˈkoːɐ̯ˌalpə, ˈkoːʁˌalpə], Slovene: Golica or Gola planina), also referred to as Koralm (German: [ˈkoːɐ̯ˌalm, ˈkoːʁˌalm]), is a mountain range in southern Austria which separates eastern Carinthia from southern Styria. The southern parts of the range extend into Slovenia. Running from north to south, it drains to the river Lavant in the west, and to the river Sulm in the east. Its highest elevation (2,140 meters) is the Große Speikkogel, a popular hiking destination and also a node for military radar airspace surveillance. In the south, in the Slovenian territory, it is contiguous with the Kozjak mountain range.

The Koralpe consists mostly of metamorphic rock, of which some parts are of considerable interest to geologists and to collectors of semi-precious stones. In and around the Weinebene (also a popular recreational and hiking area) there are pegmatites which contain significant amounts of spodumene, making this area the largest known lithium deposit in Europe. Quartz and feldspar, together with the dense forests, provided the basis for a glass and porcelain industry in earlier times.