Ontology deals with questions concerning what things exist, and how such things may be associated according to similarities and differences and related within a hierarchy. Ontology provides a rigorous way to develop a general definition of a mineral species. Properties may be divided into two principal groups: an intrinsic property is characteristic of the object and is independent of anything else; an extrinsic property depends on the relation between the object and other things. A universal is an entity that is common to all objects in a set. Here the objects are mineral samples, each entity is a specific property of these minerals, and the set of objects is all mineral samples of that mineral species. The key intrinsic properties of a mineral species are its name, its end-member formula and Z (the number of formula units in the unit cell), its space group and the bond topology of the end-member structure. These are also universals as they are common to all mineral samples belonging to that mineral species. An archetype is a pure form which embodies the fundamental characteristics of an object. Thus the archetype of a mineral species embodies the above set of universals. Real mineral samples of this mineral species are imperfect copies of that archetype, with a range of chemical composition defined by the boundaries between end-member formulae of this and other end members of the same bond topology. The result is a formal definition of a mineral species: A specific mineral species is the set of imperfect copies of the corresponding archetype and is defined by the following set of universals: name, end-member formula and Z, space group, and bond topology of the end-member structure, with the range of chemical composition limited by the compositional boundaries between end members with the same bond topology.

本体论解决的问题是存在什么事物，以及如何根据相似性和差异以及在层次结构内的相关性将这些事物关联起来。本体提供了一种严格的方法来发展矿物质的一般定义。属性可以分为两个主要组：内在属性是对象的特征，与其他任何事物无关；内在属性是对象的特征。一个外在属性取决于物体和其他事物之间的关系。一个普遍的是集合中所有对象共有的实体。这里的对象是矿物样品，每个实体都是这些矿物的特定属性，对象集是该矿物物种的所有矿物样品。矿物质的关键内在性质是其名称，其端成员式和Z（单位单元格中公式单位的数量），其空间组和末端成员结构的键拓扑。这些也是通用的，因为它们是属于该矿物物种的所有矿物样品所共有的。原型是体现对象基本特征的纯形式。因此，矿物物种的原型体现了上述通用性。该矿物种类的真实矿物样品是该原型的不完美副本，其化学组成范围由该端基分子式与同一键拓扑的其他端基分子之间的边界定义。结果是对矿物物种的正式定义：一种特定的矿物物种是相应原型的不完美副本的集合，并由以下通用集合定义：名称，端成员公式和Z，空间基团和末端成员结构的键拓扑，化学组成的范围受到具有相同键拓扑的末端成员之间的组成边界的限制。