 The Porphyry and Diabase Quarrying Company Ltd T. Ko¶ciuszki Str. 10 32-065 Krzeszowice Poland tel. (+4812) 2820619 tel./fax (+4812) 2822600 Email: zarzad@kruszywa.com        Aleksander Kępka AKOMI Kraków | The origin of the rocksThe Kraków region is an area of a very complicated and varied geological structure, which is the result of formation processes taking part during many geological eras and periods, each of them characterised by specific types of rocks and tectonic structure. Particularly important was the intensification of volcanic activity during Permian period, 270-230 million years ago, which left many traces in the area around Krzeszowice near Kraków. Cross section of Krzeszowice Trough south of Dubie (geological periods)  1. Devonian, Lower Carboniferous 2. Upper Carboniferous 3. Middle Jurassic 4. Upper Jurassic 4. Cretaceous 5. Miocene (Gadziński, 1972) Magma got out onto the earth’s surface and formed, among older rocks, igneous rocks of different sizes and shapes, or poured out in streams directly onto the surface. The porphyry and diabase deposits are the effect of this volcanic activity. Quartz porphyry can be found south and north of Krzeszowice in two intrusive formations. The first of them, known as laccolite of Zalas, has the shape of a loaf of bread and is situated between the villages of Głuchówki, Zalas, Frywałd, and Baczyn. The other, to the north of Krzeszowice, was exploited in the village of Miękinia from the beginnings of the 18 th century until1976. The last Polish king, Stanisław August Poniatowski visited the quarry in Miękinia in 1787. Porphyry started to be exploited there on a greater scale in 1852. As estimated, the size of the porphyry resources in the “Zalas” deposit is of about 70.7 million tons. The annual production is of almost 800,000 tons. The porphyry deposit in Zalas is the only one exploited in Poland. Diabase, which can be found among rock material of the Kraków region, is a rare kind of mineral. It is extracted at the “Niedzwiedzia Góra” deposit. The state-owned Industrial Stones Quarrying Company exploited the quarry up to 19 July, 2000 when the exploitation was taken over bythe Porphyry and Diabase Quarrying Company Ltd At present the resources are of about 4.5 million tons. The average annual production is of about 150,000 tons. The author of the designation “diabase” was Professor Rozen from the Academy of Mining and Metallurgy in Kraków, who used the name to describe the mineral formerly known as a kind of basalt. Basalt and diabase, being both of eruptive origin and of similar chemical constitution, are related minerals from the petrographic point of view. However, the designation “basalt” is used to describe younger rocks. As the origins of the “Niedzwiedzia Góra” deposit date back to the Permian period, a different designation is more appropriate. Physico-mechanical characteristics of porphyry and diabase, and of stone material produced from them, are being investigated for the Porphyry and Diabase Quarrying Company Ltd by research institutes and laboratories, such as:
The following standards are used in research:
The sort of material is defined according to the following standards:
The results of the most recent (1998-2000) studies of the physico-mechanical characteristics are the following:
Chemical composition:
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