I certainly respect your opinion, and thank you. I always wonder though, why I keep seeing the same matrix in so many rocks that make them look very, very similar. The protruding helix type formation looks like a Y and it twists around itself into one stem. Not all quartz looks like this at all. Around here however, in my region of the world, I am seeing this same shape and pattern over and over and over, in various stages of erosion. If it isn’t some type of coral then what is it that causes so many “rocks” of all types to form identically?
@ann-embury It principally has to do with the geology of the formation you are collecting these specimens at. There are a number of different factors which could lead to a regularity in the formation and shape of crystalline minerals. A big factor is geological forces and geochemistry.
An area like Tucson has experienced considerable volcanic activity which resulted in significant geological and geochemical forces which could account for the regularity of formation in the specimens you have been collecting. Most of specimens you have posted seem pretty consistent with the geology of an area that has experienced considerable volcanic activity and alluvial erosion. Depending on the geochemistry of that volcanic activity, minerals can demonstrate a pattern of crystalline form.
A good example from my own experience is collecting calcite geodes and selenite crystals in the Pierre Shale of Nebraska in my teens. The area is principally sedimentary strata, but due to volcanic activity on the ancient sea floor of the Western Interior Seaway (and the eventual evaporation of that seaway) you get a lot of minerals that form amidst the sedimentary rocks. Many of the selenite crystals were fern shaped and the geodes were similarly shaped both externally and internally due to local geological conditions during their formation.
Another issue with a horn coral ID is that the geology surrounding Tucson is principally composed of Jurassic and Cretaceous igneous rock such as granite. The age of the geological formations around Tucson are thus too young to contain horn coral fossils since horn corals did not survive the Permian extinction and because igneous rocks do not contain fossils because the volcanic activity which formed them would destroy the taphonomic processes which lead to fossilization.
What is it? from the myFOSSIL app 3 years ago 3 years ago3 years ago
Greetings @ann-embury ! This appears to be a piece of quartz or similar crystalline mineral/rock.
Nice crystals but Not a fossil
Fossilized horn coral?
@ann-embury I am afraid it is not a horn coral.
I certainly respect your opinion, and thank you. I always wonder though, why I keep seeing the same matrix in so many rocks that make them look very, very similar. The protruding helix type formation looks like a Y and it twists around itself into one stem. Not all quartz looks like this at all. Around here however, in my region of the world, I am seeing this same shape and pattern over and over and over, in various stages of erosion. If it isn’t some type of coral then what is it that causes so many “rocks” of all types to form identically?
@ann-embury It principally has to do with the geology of the formation you are collecting these specimens at. There are a number of different factors which could lead to a regularity in the formation and shape of crystalline minerals. A big factor is geological forces and geochemistry.
An area like Tucson has experienced considerable volcanic activity which resulted in significant geological and geochemical forces which could account for the regularity of formation in the specimens you have been collecting. Most of specimens you have posted seem pretty consistent with the geology of an area that has experienced considerable volcanic activity and alluvial erosion. Depending on the geochemistry of that volcanic activity, minerals can demonstrate a pattern of crystalline form.
A good example from my own experience is collecting calcite geodes and selenite crystals in the Pierre Shale of Nebraska in my teens. The area is principally sedimentary strata, but due to volcanic activity on the ancient sea floor of the Western Interior Seaway (and the eventual evaporation of that seaway) you get a lot of minerals that form amidst the sedimentary rocks. Many of the selenite crystals were fern shaped and the geodes were similarly shaped both externally and internally due to local geological conditions during their formation.
But, neither possessed any diagnostic features that lead myself or other identifiers to conclude the specimens were of an organic origin.
Another issue with a horn coral ID is that the geology surrounding Tucson is principally composed of Jurassic and Cretaceous igneous rock such as granite. The age of the geological formations around Tucson are thus too young to contain horn coral fossils since horn corals did not survive the Permian extinction and because igneous rocks do not contain fossils because the volcanic activity which formed them would destroy the taphonomic processes which lead to fossilization.
It’s quartz now, but it wasn’t always.