Which mineral is known to fizz with hydrochloric acid only when powdered?

The mineral that is known to fizz with hydrochloric acid only when powdered is dolomite. This reaction occurs because dolomite contains calcium carbonate (CaCO3) but in a slightly different crystalline form than calcite. When dolomite is intact, the acid cannot easily react because both magnesium and calcium ions are tightly bound within the mineral’s structure. However, when dolomite is powdered, the increased surface area allows the hydrochloric acid to interact more effectively with the mineral, releasing carbon dioxide gas and resulting in fizzing.

In contrast, calcite, another carbonate mineral, will fizz vigorously with hydrochloric acid regardless of its physical state because it is primarily composed of calcium carbonate and is more reactive with the acid than dolomite. Gypsum and quartz do not react with hydrochloric acid at all, regardless of whether they are powdered or not, because they do not contain carbonate groups. Thus, the unique behavior of dolomite in this scenario is indicative of its composition and crystalline properties.