Durable Vein Quartz

By William T. Hathaway

Vein Quartz

Now and then, a student asks about common quartzite rocks found scattered throughout many local fields. My two roadside pictures (numbered “1” and “2”) were taken at separate sites; they offer a neat explanation as to how some quartzite (vein quartz) may have formed and remain exposed in loose field soils.

Since quartzite is a conditional form of quartz, its hardness resists weathering as its surrounding rock is broken down into soil. Vein quartz may have fissure streaks of red hematite or yellow limonite; aged specimens are occasionally stained green where water has managed to penetrate fissures, leaving biological organisms such as molds and fungi.

I must confess that this explanation is hypothetical at best — vein quartz can form by means of many variable conditions.

See also further discussion of vein quartz.