A Geode with a Face..WOW

When a friend{fellow rock lover} showed me this , i thought "Photoshop!!!"  Trust the Geology page, yes! Next i though , but what do i say??? Answer would be "I want, make that I NEED this. I wanna write a post about this."  "is that a face? Pareidolia? Halloween mask, dunno. but it does look more like Mardi Gras with all those twinkling, sparkling crystals.  

 

   

geologypage.com

Thunder Egg | Geology Page

Geology Page

9–11 minutes

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Thunder Egg

A Thunder Egg “Thunderegg” is a nodule-like rock, similar to a filled geode, that is formed within rhyolitic volcanic ash layers. Thundereggs are rough spheres, most about the size of a baseball—though they can range from less than an inch to over a meter across. They usually contain centres of chalcedony which may have been fractured followed by deposition of agate, jasper or opal, either uniquely or in combination. Also frequently encountered are quartz and gypsum crystals, as well as various other mineral growths and inclusions. Thundereggs usually look like ordinary rocks on the outside, but slicing them in half and polishing them may reveal intricate patterns and colours. A characteristic feature of thundereggs is that (like other agates) the individual beds they come from can vary in appearance, though they can maintain a certain specific identity within them.

Thunder Egg is not synonymous with either geode or agate. A geode is a simple term for a rock with a hollow in it, often with crystal formation/growth. A thunderegg on the other hand is a specific geological structure. A thunderegg may be referred to as a geode if it has a hollow in it (see illustration of Gehlberg specimen), but not all geodes are thundereggs because there are many different ways for a hollow to form. Similarly, a thunderegg is just one of the forms that agate can assume.

Many thundereggs found at Rockhound State Park are spherical and consist of two distinct parts: a dark-gray to pinkish outer part and a white, blue, or gray inner part, or core, which is recognizable as agate, chalcedony, and quartz crystals, all forms of the compound SiO2. In many examples, these two parts can be described as a shell and a filling. However, some thundereggs, or spherulites, do not contain the filling; they are composed of solid dark-gray to pinkish shell material (Fig. 3) or are partly hollow. Geologically distinct processes form the two parts of the thundereggs. The outer part of the thundereggs is formed by complex magmatic processes (i.e. as spherulites), and then the inner part is formed and modified by multiple cycles of late-stage hydrothermal fluids. The processes that form geodes and thundereggs are complex and are controlled by constantly changing physical and chemical conditions, such as temperature, pressure, depth of formation, composition of the magma, composition of the ground water, and composition of the host rocks.

Occurrence

Thundereggs are found globally wherever conditions are right. In the USA, Oregon remains one of the most famous thunderegg locations. Germany is also an important center for thunderegg agates (especially sites like St Egidien and Gehlberg). Other countries known for their thundereggs include some places in Africa, Poland, Romania, Turkey, Mexico, Argentina, Canada, Australia and France.

Formation

Thundereggs are found in flows of rhyolite lava. They form in gas pockets in the lava, which act as molds, from the action of water percolating through the porous rock carrying silica in solution. The cooled bubbles were gradually filled by water percolating through the porous rock carrying rich quantities of silica (quartz). The deposits lined and filled the cavity, first with a darker matrix material, then an inner core of agate or chalcedony. The various colors come from differences in the minerals found in the soil and rock that the water has moved through.

The agate, chalcedony, and quartz veins and open-space-fillings within voids in the spherulites formed later by multiple cycles of hydrothermal fluids. Hydrothermal fluids are a mixture of late-stage fluids escaping the magma and local ground water. The fluids contain some elements from the original magma and also dissolved minerals from the country rock. The amount of ions that the fluid can dissolve depends upon pH, temperature, pressure, and composition of the fluid. The hydrothermal fluids move through fractures in the rocks, which crosscut the igneous textures, and form veins or banded agate, chalcedony, and quartz. Some of these fluids seep through microscopic pores and into spherulites and gas pockets in the volcanic rocks, and they precipitate crystals along the walls of the cavity, forming geodes and geode-like spherulites. Other fluids seep through fractures and gas and other void spaces in the spherulites. Because of their formation by multiple hydrothermal events, each thunderegg provides clues as to its unique formation.

Different temperatures and fluid compositions would account for the variety of textures found within any given thunderegg or geode. By carefully studying the crystal fill and textures in spherulites and geodes, geologists can piece together the different processes through time that formed them. The banding found within some spherulites and geodes consists of multiple layers of different colored agate, chalcedony, and locally quartz, and may have been formed by fluids supersaturated in silica (Fournier, 1985a). Supersaturated solutions are solutions that contain excessive silica in solution. The presence of silica minerals within the thundereggs and geodes indicates that the fluids were saturated in silica. Saturated fluids are fluids that contain enough silica in solution without precipitating silica minerals. When a silica-saturated solution cools slowly, crystalline quartz is deposited at approximately 200°–340° C (Fournier, 1985a). Rapid cooling of a silica-saturated fluid allows supersaturated solutions to form that precipitate chalcedony or amorphous silica. These supersaturated fluids are unstable and quickly deposit thin layers of chalcedony or amorphous silica, typically at lower temperatures (<200° C). The fluid loses silica due to precipitation and becomes saturated with silica but as the fluid continues to cool rapidly, it becomes supersaturated with silica again. An increase in salinity (such as NaCl) increases the solubility of silica at higher temperatures and also produces saturated silica solutions (Fournier, 1985a). Super­saturation of the fluids can also occur by mixing of different hydrothermal fluids, especially with different pHs, and by reaction of hydrothermal fluids with volcanic gases.

The different colors of the bands are a result of trace amounts of impurities, such as iron (red), manganese (black, pink), cobalt (blue, violet-red), copper (green, blue), chromium (orange-red), nickel (green), etc. Faceted quartz crystals indicate that the fluids were somewhat supersaturated with silica and that precipitation occurred under relatively slow-changing conditions (Fournier, 1985a).

Not all geodes are spherulites formed by magmatic processes; other natural processes form some geodes. Lower-temperature ground water percolates through the cooled volcanic rocks and dissolves additional minerals. These fluids are typically low temperature (<200° C), although locally higher-temperature (200°– 300° C) ground waters may be present, especially adjacent to the volcanic vents. These fluids move through microscopic pores in the rock by a process called “diffusion.” During diffusion, some ions in the fluid collect into void spaces and gas pockets in the rock, whereas other ions cannot pass through. This collection of ions surrounding these void spaces may actually, in some cases, form the hard outer shell that is characteristic of geodes. The outer shell may be strengthened by the precipitation of some ions that were excluded during crystallization of agate, chalcedony, and quartz and concentrated in the remaining fluid. Fluids also enter the void spaces through fractures. The void spaces may have originally formed by gas pockets within the magma or by prior dissolution of spherulites or other features within the volcanic rock.

How do the Thunder Egg/spherulites become hollow?
this is difficult to demonstrate directly, we speculate that the hollow centers of spherulites are formed by nucleation, coalescence, and expansion of vapor bubbles at high temperature, resulting in a hollow center that can be filled later by silica. The vapor bubbles would have formed as a result of crystallization of quartz, feldspar, and magnetite, which contain no water, from rhyolitic magma, which contains a small amount of dissolved water at atmospheric pressure (Taylor, 1986). Calculations of the volume of water vapor that could have formed from anhydrous crystallization suggest that the volume would be more than enough to generate the size of hollow cavities seen in spherulites. The reason that some spherulites are hollow and others are not may be related to the rate and depth of crystallization and to the resultant ability or inability of vapor bubbles to nucleate and coalesce.

Reference:
Wikipedia: Thunderegg
Oregon State Rock:State Symbols USA
The Formation of Thundereggs: Robert Paul Colburn PDF
Rock Hound State Park and Spring Canyon Recreation Area, Recreation Area: New Mexico Geology, v. 22, no. 3, p. 66-71, 86.

Welcome October !

welcome to October 

 

long night no birds sing

dry leaves rustle in the dark

 coffee by the fire

 

 

 

 There is something so warm and cozy about October, there is something dark, slightly scary about it,and there is something to sitting quietly,  thinking and resting in the dwindling sunshine.  

In my not so humble opinion October is a good time to treat yourself to some "me" time,   so raise a cup and toast make a toast to your inner child.  "klink"

Guest blogger ! Karyn Hede. , tiny seawater pockets 390.

 Tiny pockets of seawater  390,million years old, Ihe tinyest pockets found at that time, filled with clues about the life that existed  in those early seas.   Written in 2022, apologies for my tardiness,  this is an exciting find to a fossil loving rock hound like me.  it will have me looking up stuff for weeks

geologypage.com

Tiniest ever ancient seawater pockets revealed - Geology Page

Geology Page

6–7 minutes

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Giant sea scorpions once roamed the ancient Devonian sea 400 million years ago. Now, researchers are learning more about that world. Credit: Aunt Spray | Shutterstock.com

Trapped for millennia, the tiniest liquid remnants of an ancient inland sea have now been revealed. The surprising discovery of seawater sealed in what is now North America for 390 million years opens up a new avenue for understanding how oceans change and adapt with the changing climate. The method may also be useful in understanding how hydrogen can be safely stored underground and transported for use as a carbon-free fuel source.

“We discovered we can actually dig out information from these mineral features that could help inform geologic studies, such as the seawater chemistry from ancient times,” said Sandra Taylor, first author of the study and a scientist at the Department of Energy’s Pacific Northwest National Laboratory.

Taylor worked with PNNL colleagues Daniel Perea, John Cliff, and Libor Kovarik to perform the analyses in collaboration with geochemists Daniel Gregory of the University of Toronto and Timothy Lyons of the University of California, Riverside. The research team reported their discovery in the December 2022 issue of Earth and Planetary Science Letters.

Ancient seas; modern tools

Many types of minerals and gems contain small pockets of trapped liquid. Indeed, some gemstones are prized for their light-catching bubbles of liquid trapped within. What’s different in this study is that scientists were able to reveal what was inside the tiniest water pockets, using advanced microscopy and chemical analyses.

The findings of the study confirmed that the water trapped inside the rock fit the chemistry profile of the ancient inland saltwater sea that once occupied upstate New York, where the rock originated. During the Middle Devonian period, this inland sea stretched from present day Michigan to Ontario, Canada. It harbored a coral reef to rival Australia’s Great Barrier Reef. Sea scorpions the size of a pickup truck patrolled waters that harbored now-extinct creatures like trilobites, and the earliest examples of horseshoe crabs.

But eventually the climate changed, and along with that change, most of the creatures and the sea itself disappeared, leaving behind only fossil remains embedded in sediments that eventually became the pyrite rock sample used in the current experiment.

Clues to an ancient climate and to climate change

Scientists use rock samples as evidence to piece together how the climate has changed over the long span of geologic time.

“We use mineral deposits to estimate the temperature of the ancient oceans,” said Gregory, a geologist at the University of Toronto, and one of the study leaders. But there are relatively few useful examples in the geological record.

“Salt deposits from trapped seawater [halite] are relatively rare in the rock record, so there are millions of years missing in the records and what we currently know is based on a few localities where there is halite found,” Gregory said. By contrast, pyrite is found everywhere. “Sampling with this technique could open up millions of years of the geologic record and lead to new understanding of changing climate.”

Seawater surprise

The research team was trying to understand another environmental issue — toxic arsenic leaching from rock — when they noticed the tiny defects. Scientists describe the appearance of these particular pyrite minerals as framboids — derived from the French word for raspberry — because they look like clusters of raspberry segments under the microscope.

“We looked at these samples through the electron microscope first, and we saw these kind of mini bubbles or mini features within the framboid and wondered what they were,” Taylor said.

Using the precise and sensitive detection techniques of atom probe tomography and mass spectrometry — which can detect minuscule amounts of elements or impurities in minerals — the team worked out that the bubbles indeed contained water and their salt chemistry matched that of ancient seas.

From ancient sea to modern energy storage

These types of studies also have the potential to provide interesting insights into how to safely store hydrogen or other gases underground.

“Hydrogen is being explored as a low-carbon fuel source for various energy applications. This requires being able to safely retrieve and store large-amounts of hydrogen in underground geologic reservoirs. So it’s important to understand how hydrogen interacts with rocks,” said Taylor. “Atom probe tomography is one of the few techniques where you can not only measure atoms of hydrogen, but you can actually see where it goes in the mineral. This study suggests that tiny defects in minerals might be potential traps for hydrogen. So by using this technique we could figure out what’s going on at the atomic level, which would then help in evaluating and optimizing strategies for hydrogen storage in the subsurface.”

This research was conducted at EMSL, the Environmental Molecular Sciences Laboratory, a DOE Office of Science user facility at PNNL. Lyons and Gregory applied to use the facility through a competitive application process. The research was also supported by a grant from the Natural Sciences and Engineering Research Council of Canada.

Reference:
S.D. Taylor, D.D. Gregory, D.E. Perea, L. Kovarik, J.B. Cliff, T.W. Lyons. Pushing the limits: Resolving paleoseawater signatures in nanoscale fluid inclusions by atom probe tomography. Earth and Planetary Science Letters, 2022; 599: 117859 DOI: 10.1016/j.epsl.2022.117859

Note: The above post is reprinted from materials provided by DOE/Pacific Northwest National Laboratory. Original written by Karyn Hede.

 

further information 

with more images 

haiku, a walk in the fog

  

 a walk in the fog

red, orange,  yellow leaves shinning

 breathing in the colors 

 

 

 

 

the second harvest, Mabon

 Mabon greetings!

The wheel of the year pauses gently today, on this day of equal light and dark, it marks the crossing from lengthening days to a time of lengthening  nights. Celebrating The Second Harvest a time, not only to celebrate and be grateful for that harvest, and preserve that which has been harvested and foraged for the months ahead.

Gaia, the Greek's primordial personification of the Earth passes her reign over summer's sunshine to her counterpart, Uranus, the Greek's primordial personification of the sky, who reigns over the chill of winter.    

 

Equal night and equal day, the Autumnal Equinox marked the calender date when the nights would not only grow longer, but the like the day also grow colder.  Weather patterns can differ widely from year to year and having at least an idea when it would no longer wise to build or plant could be useful. 

  Balance is also central to how the Autumnal Euimox is celebrated. Balancing honoring the Cestial beings,work, with a gathering of friends and reletaives surely made scence.  Sharing and bartering were essentials of life then also, as was the celebration the bonds that held a village or family together.  

 

 

Archaeologists Find 24 Bronze Statues ‘Without Equal’ Preserved in Tuscany for 2,300 Years,guest blogger Andy Corbley

 Have you ever what winders made by ancients remain hidden?   I also!  

 

 

 

Archaeologists Find 24 Bronze Statues ‘Without Equal’ Preserved in Tuscany for 2,300 Years That 'Rewrite History'

Andy Corbley

3–4 minutes

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credit Italian Ministry of Culture, Tourism, and Antiquities

Whilst excavating Roman-era baths in the Tuscan hills outside Siena, archaeologists have stumbled upon what is quite simply one of the most significant discoveries ever found in Italy.

24 bronze statues in perfect condition emerged, sometimes first with a hand, or with a head, from the mud around an area famous for thermal hot springs, along with a hoard of over 5,000 Roman coins in bronze, silver, and even gold.

The incredible statues, which haven’t even turned green with age thanks to the oxygenless environment of the mud, date to the Republican period of the 200s BCE, a time of great upheaval in Tuscany when the Romans were in the process of fully subsuming the Etruscan civilization of the Italian Peninsula which predated them.

The discovery site in the modern town of San Casiano dei Bagni, was once an Etruscan settlement, and the baths were used first by them and by the Romans afterwards until the century of their collapse 600 years later.

The lead excavator, Jacopo Tabolli, a historian at the University for Foreigners in Siena, spared no hyperbole in describing the find—starting by saying it would “rewrite history,” of the Peninsula.

He called it “without equal… the largest deposit of bronze statues of the Etruscan and Roman age ever discovered in Italy and one of the most significant in the whole Mediterranean,” adding that nearly all statuary art from this period is in terracotta.

The statues depict deities like Apollo and Hygieia, a Greek goddess of health first worshiped in Corinth.

credit Italian Ministry of Culture, Tourism, and Antiquities

The excellent state of the statues has also preserved inscriptions in the Etruscan language and Latin. Some are honors for the gods but there are also the names of important and powerful Etruscan families like the Velimna of Perugia, and the Marcni.

MORE ROMAN DISCOVERIES: Spy Satellite Photos Reveal Hundreds of Long-Lost Roman Forts, Challenging Decades-Old Theory

For the Sindaco, or the mayor of San Casiano dei Bagni, he sees a little more green in the bronzes than the archaeologists.

“This discovery,” he said, “offers San Casciano not only a cultural and touristic opportunity, but a true occasion for rebirth.”

NEWS JUST LIKE THIS: Tiny Italian Town Dug Up an Extremely Rare Roman Temple while Trying to Build Supermarket

“There will be born a new museum, that will host the exceptional statues and an archeo-park; two new places that will, for the town, be a real motor of development and add an enthusiasm to young archaeologists around the world who will come to see and work here.”

Before they can return to the museum, the statues were taken to a preservation center in Grosseto.

haiku~~~~~yard art????

 

 

 

 HOURS SPENT TOGETHER

SO MANY MEALS WE SHARED

YOU WERE BY MY SIDE

 

THRU SADNESS AND JOY 

JUST COULDN'T RECYCLE YOU 

NOW YOU ARE YARD ART 

YOU WERE ALWAYS THERE