Zakázanka
Menu- Welcome to Zakázanka
- In search of bygone eons
- An example of a reverse fault and a crush zone
- Folds
- A fault separating two geological periods
- Iron ore
- Exposed boundary
- What is growing here (1)
- What is growing here (2)
- Little warm lovers
- Sun lovers
- Bedrock
- Fluvial sandy gravels of the vineyard terrace
- Local denizens of the air
- A window into Prague's geological past
- Iron ore on the zoo grounds
- The rock face bears silent witness
- Regeneration of the rocky steppe
Iron ore
Iron ore in Prague Zoo? Yes, indeed – around this path we can find a seam of first-rate iron ore, the extraction of which was actually once contemplated. The thickness of the seam is, however, so meager that extraction would not pay off.
To protect against the danger of blocks of rock collapsing, it was necessary to secure this exposure with nets. A more accessible iron-ore exposure is found near the path under the Černohouska building.
The volcanic tuffs
The volcanic tuffs of which the rock is composed in that location are partly saturated with a dark-red mineral called hematite (ferric oxide Fe2O3, in chemical nomenclature). These ferruginous tuffs form two massive layers, of which the lower, 130 cm thick, contains up to 57 percent of iron. The iron ore is thus of high quality but, due to its scant quantity, of no practical significance.