Difference between revisions of "Calcareous rock"

'''calcareous rock''' ([[Category:Noun]][[:Category:Noun|noun]], ''pl.'' calcareous rocks; [[Category:Ecology term]][[:Category:Ecology term|ecology term]], [[Category:Substrate term]][[:Category:Substrate term|Substrate term]]) – a [[calcite]] (limestone), i. e., a rock consisting of calcium carbonate, generally with a high pH (pH > 7), usually (vigorously) bubbling when treated with a strong acid (e. g., 10% HCl). ''Note:'' In a strict sense the term ''[[calcareous]]'' only applies to rocks that ''consist of'' calcite, i. e., that are entirely composed of calcium carbonates. In contrast, [[calciferous]] rocks are not necessarily composed entirely of calcite but only ''contain'' calcium carbonate. This distinction is, however, rather academic, because there are hardly any natural rocks that are pure calcites. Thus essentially all calcites contain impurities of other minerals. The term ''calcareous rock'' is frequently used as ''opposed to'' [[siliceous rock]] even though siliceous rocks are not necessarily devoid of calcite, but may contain traces or even relatively large amounts of calcium carbonate. More accurately rocks devoid of any calcium carbonate should therefore be referred to as [[non-calciferous]]. The HCl-test frequently applied to detect calcium carbonate can be misleading if a rock contains magnesium carbonate that also shows a (weak) "bubbling" reaction.