• A well-composed fanning wedge-shaped mineral specimen with two square formations and a spherical one covered with light golden-tan druzy, and surrounded by larger white quartz crystals.
  • Detail of the quartz crystals, showing alligator growth highlighted by golden iron staining in the inverted portions. The quartz has white phantoms and small black inclusions.
  • Detail of milky phantom growth inside colorless quartz points spotted with fine black inclusions, and with iron staining emphasizing the textured sides.
  • Another angle view of the mineral specimen, quite large in a hand.
  • Full close view of the mineral, with the pepper-spots of iron inclusions apparent. Quartz points sharply reflect light showing good form.
  • Detail of the larger cube and spherical formations covered with druzy, with a red ring of iron-staining. Reflecting quartz faces show clean growth. Calcite with poorer luster like brown rice grains covers the top of the mineral.
  • Detail of the side of the specimen, displaying multiple growth types at once. The top of the specimen is covered with druzy with quartz points on the right. In the foreground the specimen is covered in rice-grain-like calcite crystals that devolve into hexagonal crystals.
  • Detail of a cluster of steep dogtooth calcite points on the edge between the light brown-yellow druzy on the right and the larger white quartz crystals on the left.
  • The calcite grains on the side of the specimen exposed to UV light, fluorescing and orange-red color.
  • Bottom of the mineral specimen exposed to UV light, with the calcite fluorescing a peachy red color in the shape of two squares.
  • Scale image of the piece on a measurng mat, wedge-shaped and measuring about five inches at its widest and less than three inches on the thin edge. It is about three inches wide.
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Quartz and calcite cluster

Quartz and calcite cluster

$65.00 USD
$65.00 USD
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Locale: Potosí Mine, Santa Eulalia, Chihuahua, Mexico

Approx dimensions: 5 x 3 x 1.5"

Approx weight: 420g

 

This quartz and calcite specimen from the Potosí Mine is one of my favorites I've seen from this locale. There are two large calcite rhombs and a spherical formation covered in quartz tinted brown-yellow with iron. On top are pellet-like calcites that look like brown rice. Where better-formed, they are small dogtooth calcite points.

Quartz points sprout out around this formation. The larger crystals display milky white phantoms inside colorless quartz. They have alligator growth forms, commonly known as "elestial" quartz, beautifully emphasized by yellow iron staining and interspersed with clusters of calcite teeth. Black iron inclusions pepper the quartz, appearing as rings, strings, or spots under magnification (you can see it if you zoom in on close shots!).

UV reactivity Under 365nm UV light, the bottom of the specimen clearly shows the rhombohedral growth of the calcite structures on the front side. It has strong orange-red fluorescence with brief phosphorescence. The smaller calcite rice grains fluoresce a lighter orange-red.

** Brittle warning: Be careful putting pressure on crystals along the edge as they may dislodge from the specimen. 

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