Are there harmful substances in cobblestones?

Answer

Dear Willie,

Two types of cobblestones were traditionally used in Belgium.

– The first type are the best known and these are magmatic rocks that were extracted in quarries in the vicinity of Quenast and Lessines (south of the language border). Also called porphyry, this rock is the result of rising magma solidifying in a pipe. This rock consists mainly of minerals such as feldspars, quartz and a small amount of other minerals such as pyroxenes and Fe-Ti oxides. These are the basic minerals that are present in every volcanic/magmatic rock and are non-toxic. After its location, this rock has undergone another alteration, as a result of which new minerals were formed at the expense of the original minerals. This gives the typical green spots that consist of the mineral epidote, which is also not toxic. Any chemical element can be found in any stone if one uses a sufficiently sensitive method of analysis. However, the magmatic rock has not known a specific enrichment for certain elements, which means that potentially harmful elements are present in extremely low to immeasurable concentrations. This means that it can be said that no harmful substances are present in these rocks.

– A second type of cobblestone consists of very hard sandstones or quartzites that were quarried from certain quarries south of the language border. These are the oldest rocks in Belgium and were formed by the recrystallization, cementing and cementation of originally sand deposits. This rock therefore consists mainly of quartz, which is not toxic either. In these rocks, the concentrations of potentially harmful elements are also extremely low to immeasurable. So it can also be said that no harmful substances are present.

There is therefore nothing toxic in the cobblestones and there is therefore no health problem whatsoever.

The only danger that could possibly exist is the long-term inhalation of the fine stone dust that would be released during the mining of the quarries or the sawing of the stones. But with normal handling of cobblestones there is no risk whatsoever.