Without Aragonite, many of Earth’s organisms could not exist. This is mineral most invertebrate organisms use to construct their shells and hard parts. So if you have ever admired a colorful seashell, you have already paid tribute to the range of colors Aragonite comes in and indirectly to the ease with which Aragonite forms at the Earth’s surface.
Aragonite and calcite are ‘polymorphs’, minerals that have the same chemical composition but slightly different crystal structures. Both minerals can occur together and are so similar to one another that distinguishing between them is seldom important to anyone but a professional geologist. Calcite is more stable and common than Aragonite under the chemistry of our modern seas, but at times in the Earth’s past, Aragonite was the more stable and common form. The two minerals are nearly identical in their physical properties.