Within zircon crystals much of the geological history of the earth is written. They revealed the presence of oceans before there was life on this planet, 4.4 billion years ago. They record the history of rock formations, ancient drainage patterns, the development of the earths crust and the growth of different parts of each crustal plate. Each zircon crystal is a puzzle waiting to be solved. Some are complex and others are simple but all are a challenge. The relative length of the crystal (aspect ratio: length to width) indicates its rate of growth; longer crystals (higher aspect ratio) grew faster, near the surface of the earth. Shorter crystals tended to be from slowly cooled rock much deeper in the crust or even in the mantle of the earth. Zircons can show the shock of meteor impacts or may themselves be from meteorites.

The variations in shape and internal texture shown by zircons can mark the origin of a soil in a forensic investigation. The soil is marked by the rocks that degraded to aid in the formation of the soil. These rocks came from the local geology and reflect the geological history of that locality. Zircons show the variety of rock formations that contributed to the soil and the relative contribution of each. The high density of zircon, 4.6 grams/cc, makes it easy to separate from the more common lighter minerals. Its high birefringence, high refractive indices, and its tendency to exhibit its tetragonal crystal structure simplify its identification in a sample. Associated minerals can often add additional context to the story revealed by the zircon crystals. In short, zircon crystals are particularly fun.

Rounded

Pupin (1980) Class P3

Pupin (1980) Class P4

Pupin (1980) Class R2

Pupin (1980) Class R3

Pupin (1980) Class S13

Pupin (1980) Class S15

Pupin (1980) Class