But, in the great majority of cases, the mineral ingredients of the rocks are either so small individually, or so broken, and rounded, and altered, that crystallography gives comparatively little aid to the practical geologist in the field.
"Geology"
James Geikie
Such can be said to be one of the laws of crystals, and as it is found that every substance has its own form of crystal, a science, or branch of mineralogy, has arisen, called "crystallography," and out of the conglomeration of confused forms there have been evolved certain rules of comparison by which all known crystals may be classed in certain groups.
"The Chemistry, Properties and Tests of Precious Stones"
John Mastin
This principle did not prove to be absolute in its application; but the amount of truth in it attracted attention to the subject of crystallography because of the help which that science would afford in the easy recognition of the general chemical composition of mineral substances.
"Catholic Churchmen in Science"
James J. Walsh