Area of Kameni vrh (Gaveznice) in Lepoglava is represented as fossil volcano, which was created before approximately 22 million years. Reason because of this volcano is called fossil is in that it was covered soon after its creation by younger sediments, and it came back on the surface in upper pliocen (approximately 2 million years ago)

Gaveznica is situated around 400 meters south of church of St. Mary in Lepoglava. Formerly the name Kameni vrh was related to the steep hill which was built of adenit, while the lower area, where the orchard of penitentiary in Lepoglava was situated, was considered Gaveznica. The name Kameni vrh was lost in use during the years, and only the name Gaveznica remained.

This area is also known as the first discovered source of agate in Croatia. It is presumed that Paulines knew for it in the Middle Ages, and some evidences show that it might have been used much earlier. It seems that even old people from the stone age knew for it, because in the cave Vinija and in the cave Velika (Velika Špilja) on Ravna gora stone knives, scrapers, stone axes and other tools were found, and in Vindija hand pins of green tuff were found. Geological exploration discovered that on the area of Croatian Zagorje there are very little rocks made of quartz or other materials that could serve for this purpose.

Agate, which is the most interesting amongst half – precious stones on Gaveznica, has nuances from the light - blue to dark – grey color.

Recently there have been discovered new sources f half – precious stones near :ret, 4 km east of Gaveznica. According to the amount, different calcedons, red jaspers, and ahat step out, though there is amethyst and normal opal present.

Lepoglava is connected with minerals and mineralogy in one more way. Exceptional work of Ivan Belostenac, Gazophylacium, printed in the year 1740, served as the source of Croatian mineralogical terminology, because it contains 270 terms belonging to mineralogy. First term we encounter is Achates, m3.p.p Akat stone.