Term	Guidance  	Possible synonyms
all	Component constitutes effectively 100 percent of the volume of the unit.	
dominant	Component constitutes more than 50 percent of the volume of the unit.	predominant
major	Component constitutes more than 25 percent of the volume of the unit.	"abundant, main, most common, primary, significant "
subordinate	Component constitutes less than 25 percent of the volume of the unit.	"inferior, secondary, subsidiary"
minor	Component constitutes less than 10 percent of the volume of the unit.	"accessory,  uncommon"
rare	Component constitutes less than 3 percent of the volume of the unit.	"sparse, trace"
variable	Component varies in proportion throughout the unit; may be rare in some parts and dominant in others.	
present	"Component is present, but proportion is unknown. The term is useful where compiling information from published maps in which the author did not specify proportions of lithologies within a map unit."	 