Aragonite is a common mineral that belongs to the class of carbonates and nitrates. It forms crystals that fall into an orthorhombic crystal system with the chemical composition Ca[CO3]. In its pure form, it is colorless and transparent.

Aragonite is a common mineral from the class of carbonates and nitrates. Chemically, it is a calcium carbonate, but it crystallizes in the orthorhombic crystal system and can occur in prismatic crystals, mineral aggregates (which can be spherical or oolitic), in banded forms, columnar and dendritic (tree-like) as well as in parallel fibrous, radially radiating or acicular forms.

In its pure form, aragonite is colorless and transparent. However, it can also appear white due to multiple light refraction as a result of lattice structure defects or polycrystalline formation and can take on a grey, yellow, red, green, violet or blue color due to foreign impurities, whereby the transparency decreases accordingly.

Aragonite is the eponymous mineral of a group of minerals with a similar structure and/or composition known as the aragonite group.

In 1796, Abraham Gottlob Werner described the mineral as a new species of his recently created mineral group. He named it after the place where it was found in the province of Aragon in north-eastern Spain.

Aragonite belongs to the carbonates, nitrates and borates, which are subdivided into anhydrous carbonates without foreign anions. It forms a series with alstonite, cerussite, strontianite and witherite as well as in the appendix with barytocalcite.

In the Lapis mineral directory according to Stefan, the white aragonite received the systematics and mineral number V/B.04-10. This also corresponds to the section "Anhydrous carbonates [CO3]2 - without foreign anions", where aragonite forms the "aragonite group" together with alstonite, barytocalcite, cerussite, olekminskite, paralstonite, strontianite and witherite (as of 2018).

As is well known, the 6th edition of Strunz's mineral systematics, which has been valid since 2001 and was updated by the International Mineralogical Association (IMA) until 2009, classifies aragonite in the newly defined class of "carbonates and nitrates" (borates form a separate class here), but also in the division of "carbonates without additional anions; without H2O". This is further subdivided according to the affiliation of the cations to certain element families, so that the mineral can be found in the subdivision "alkaline earth (and other M2+) carbonates" according to its composition, where it forms the "aragonite group" with the system no. 5.AB.15 only together with cerussite, strontianite and witherite.