Flint: Our Rock of Ages

Used Since the Dawn of Humanity

- STEVE VOYNICK

In today's world, we sometimes forget that during most of humankind's existence, the most critical material was stone-and that the most widely used type was flint (also called chert). Readily available, extraordinarily durable, and eminently workable, flint was the first mineral commodity to be systematically mined and traded. Vital to early human survival and development, it is truly our "rock of ages."

Although no longer of major economic or technological importance, flint still captures the attention of geologists, paleontologists, archaeologists, historians and lapidaries. The word "flint" also appears in the names of many topographical features, towns, and even a national monument. Two states honor flint as their official gemstone or rock.

FLINT OR CHERT?

The words "flint" and "chert" refer to the same fine-grained, chemical-sedimentary rock. Geologists favor "chert," while historians and paleontologists prefer "flint." Archaeologists consider chert as the raw material from which flint artifacts are made. Some writers use "flint" for nodules and "chert" for bedded occurrences. Others consider flint a dark variant of chert or a high-grade chert with finer grain and superior workability. This article uses both terms depending on geological or historical contexts.

Flint is an impure form of chalcedony, which consists of interlocked, microscopic crystals of quartz (silicon dioxide, SiO2). Because it is impure and varies in composition, flint is technically a rock. Its main impurities are mogánite (hydrous silicon dioxide) and related forms of hydrated silica.

PROPERTIES & OCCURRENCE