Chemical Formula

Definition

The format for the chemical formula is based on the reported formula from the literature source for the mineral. In many cases, the formula is base on the structural interpretation of the mineral, especially the silicates.

The chemical formula is closely matched to the mineral's crystallographic unit cell dimensions and "Z" value.

Special symbols are used where a hole (vacancy) is present in the formula. For this database, the "[ ]" square brackets are used to signify this vacancy.

e.g.: ([ ],Fe,Mg)(Mg,Al,Fe)5Al4Si2(Si,Al)2(B,Si,Al)(O,OH,F)22

Rare Earth Elements in mineral formulae are denoted by the symbol REE.

e.g.: (Na3(Ca,REE,Sr)3(CO3)5)

For Further References on Chemical Formula

Search the Mineralogy Database

Example Subject Searches

Example: To find minerals with Si₂O₇ in the chemical formula try "Si2O7".
Example: "PO4,CO3" finds all minerals with PO₄ and CO₃ in that order of occurrence.
Example: "PO4" "CO3" finds all minerals with PO₄ and CO₃ without regard to order of occurrence.

Search Engine Note:

The search engine parses the chemical formula's in a certain way. For example: [ ]Ca2(Fe2+)3Al2(Si6Al2)O22(OH)2 is parsed as ca2 fe2 3al2 si6al2 o22 oh. Notice the brackets and parenthesis are ignored and are counted as spaces. A search on (Fe2+) will fail but a search on fe2 will be successful.