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
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.