Near the village of Milínov in the southern Pilsen Region, there is an interesting rock formation made of a rock called silicite (popularly known as bulijník) and it is called Vyhlídka Mariina skála. Silicites are rocks formed in the Upper Proterozoic period (Palaeohory, Neoproterozoic) in Barrandien (area between Prague and Pilsen) - the age of these rocks is more than 600 million years. In this locality, the rock formation forms a morphologically striking dissected stone suk (nice Czech name - kamýk), emerging as part of a silicite belt stretching from Klatov through Plzeň, then across the northern edge of Prague to Brandýs n. Labem. Erosion-resistant very hard silicites are dissected from the surrounding soft chert shales and siltstones by the processes of glacial frost weathering, erosion and denudation. The silicities are characterized by a gray to black-gray color, changing in some parts to violet-gray to rusty shades. They are mostly massive, partly with a streamlined planar structure. Silicities tend to be interwoven with numerous veins of secondary rock - whitish-colored quartz, which was formed by hydrothermal precipitation and thus filled cracks (so-called secondary hydrothermal crack healing). Silicites are composed of quartz (SiO2 – silicon dioxide). Trace amounts of carbonaceous or hematite pigment and fine muscovite are present, which is why it has a gray to black or rust color. Other similar formations in the vicinity – Ostrá hůrka near Staréno Plzeň, Andrejšky, Těnovická skála, Radyně hill, etc.
The origin (genesis) of silicites in the Czech massif has not yet been clearly explained. According to some expert theories, silicites were formed with the contribution of living organisms with siliceous shells by sedimentation and diagenesis (organogenic origin of the rock) or by precipitation of silicic acid gel and silicic solutions from hot hydrothermal springs on the sea floor (chemogenic origin of the rock). However, one thing is clear. These rocks formed in a deeper ocean at the edge of the landmass (later called Gondwana) near the Earth's South Pole more than 600 million years ago.
49°39'19.1"N, 13°33'54.8"E
