Desert Varnish Sandstone — Polished Face

$23.42
Chemical FormulaQuartz sandstone + manganese-iron oxide varnish
Crystal System
Mohs Hardness7
Specific Gravity2.65
LusterDull to waxy
TransparencyOpaque

Desert varnish — the dark rind coating canyon walls and boulders throughout arid regions — is deposited by microorganisms over thousands of years. Bacteria concentrate manganese fr…

37 in stock

SKU: TC-GEO-0881
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Description

Science and beauty are rarely in conflict. Here they converge. Desert varnish — the dark rind coating canyon walls and boulders throughout arid regions — is deposited by microorganisms over thousands of years. Bacteria concentrate manganese from windblown dust and bind it to rock surfaces in a manganese-iron oxide layer sometimes only micrometers thick. Ancient petroglyphs are created by scratching through varnish to expose lighter rock — the varnish dates the minimum age of the art.

This specimen originates from Colorado Plateau, Utah, USA, one of the world’s most significant localities for this type of material. Collectors and scientists have drawn from this region for generations, and for good reason: the combination of geological conditions here produces specimens of exceptional quality and clarity.

Every specimen is unique. Photographs approximate the visual experience, but the real thing — its weight, its luster under a raking light, the way it catches the corner of your eye — can only be experienced directly.

Formation

This specimen formed through geological processes operating over timescales that dwarf human history. The specific combination of chemistry, temperature, pressure, and time at this locality produced material of exceptional quality that makes it a valued addition to any serious collection.

Locality

Desert Varnish Sandstone — Polished Face from Colorado Plateau, Utah, USA. This locality is known for producing specimens of exceptional quality.

Collector Notes

The luster is maximized by low-angle raking light — try a single spotlight.