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@causticautistic.bsky.social Sep 20, 2026, 6:50 PM

Was going through some old pix and ran across these. I'm a sucker for old museum displays.

#chicago #FieldMuseum #field #museum #displays #geology #minerals #helicites #coquina #marble #geode #crystals #monochrome #blackandwhite #bwphotography #bwphoto #bnw #b&w #photography #photosky

"HELICTITES WYANDOTTE CAVE WYANDOTTE, INDIANA
HELICTITES
THESE ARE SMALL DEPOSITS OCCURRING ON CAVE WALLS ND CEILINGS NLIKE THE STALACTITES AND STALAGMITES. WHICH ARE STRAGHT, HELICTITES BEND IRREGULARLY AND ASSUME THEIR CROOKED FORM AS A RESULT OF THE CHANCE ORIENTATION OF THE CRYSTALS AT THE GROWING END OF THE TUBE."

And there's a chunk of helicites that look like a Renaissance painting of one the circles of hell, a seething mass of body parts.

Coquina
St Augustine, Florida

Coquina (/koʊˈkiːnə/) is a sedimentary rock that is composed either wholly or almost entirely of the transported, abraded, and mechanically sorted fragments of mollusks, trilobites, brachiopods, or other invertebrates. The term coquina comes from the Spanish word for "cockle" and "shellfish".

NORMAL FAULT IN MARBLE
THIS BLACK MARBLE WAS ORIGINALLY CROSSED BY A THIN VEIN OF WHITE CALCITE. IT BROKE NEAR THE CENTER AND THE PART AT THE RIGHT SLIPPED DOWN ONE INCH AS IS SHOWN BY THE DISPLACEMENT OF THE SMALL WHITE VEIN. THE FAULT FISSURE WAS LATER FILLED BY A VEIN OF WHITE CALCITE.

And there's a tall rectangular piece of black marble as described.

Geode
Lined with quartz and calcite crystals
Keokuk, Iowa

And there's a geode that's been cut open to reveal.... quartz and calcite crystals.

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