FMF - Friends of Minerals Forum, discussion and message board

[David Dinsmore]

Fantastic!

[Don Lum]

Hello Pierre,

You have some beautiful scepters. Thanks for posting them.

Regards,

Don

[Tracy]

Wonderful pieces, congratulations!

- Tracy

[am mizunaka]

[Pierre Joubert]

Hi David, Don and Tracy. Thanks for the comments. Fantastic sceptered specimen Am! QtzLil1.jpg

Here are few more.

[Pierre Joubert]

Hi, it's me again with more scepters.

[am mizunaka]

A few from the Tucson show this year.

[Scott LaBorde]

So after putting a lot of effort on theorizing how this scepter/reverse scepter configuration occurs together here's my try at a guess.

First, I'm thinking the solution in which the quartz crystals are growing is such that the conditions for growth sit right at the border of dissolution and growth. In other words crystal structure is being added and dissolved at the same time. This would account for what appears to be melted or curved features you see in some specimens. It would also account for why we don't just always see melted scepter structures -- as the structure is quickly repaired as it dissolves preserving the nice crystal shape.

Now, to account for differences in structure within the same pocket, geode, ect, I'll be making big leaps of assumptions that may or may not be possible due to my ignorance to the physical and chemical process of crystal growth.

First, the fluid would have to be some viscous fluid in which mixing does not occur quickly. And perhaps non-viscous fluids can also have this same property. The attached drawing I made demonstrates how certain flow patterns, eddies, or blebs of fluid might contain properties of dissolution. This property of dissolution could be a combination of temperature, acid, or some other chemical property that dissolves the quartz. Now I have arrows demonstrating a possible flow pattern, however, blebs of dissolving fluid that do not move around much if at all may be possible too. In this case the picture would not have arrows but small zones (circles) of quartz dissolving properties.

So how would I explain how most scepters are larger at the termination? Another leap here -- perhaps the prism faces of quartz (the shaft) is much more susceptible to dissolution than the rhombahedral faces (the termination), thus the majority are normal scepters. I know this seems to contradict how reverse scepters are formed. But in these cases I believe the flow pattern or blebs are taking precedence overpowering the terminations resistance to dissolving.

I can imagine a scenario where a very slow moving bleb dissolves a termination on one crystal, the bleb now containing the silica from the dissolved crystal shifts slightly hovering around another crystal and now perhaps losing some of its dissolving properties deposits it on next crystal forming a normal scepter.

Whether or not such concentrated blebs (zones) or flow patterns are even possible in micro environments may well blast my theory out of the water. Perhaps there is more than one way to form a scepter. If this is the case than trying to come up with a single explanation for scepter growth is made overly complex or impossible based on the physical evidence and variety of scepters we see. Perhaps similar to Ptolemaic astronomy where in a geocentric system things become very complex trying to explain how the planets are moving around.

[Scott LaBorde]

Okay, I do realize my theory is full of holes and most likely easily dismissed, but I'm not worried about being blatantly and publicly wrong with my silly assumptions especially knowing that I can learn from it. So, please don't worry about letting me know how I'm wrong. I was mainly interested in keeping the topic of scepter formation going. Obviously I'm intrigued by how it happens.

[Reef]

Very interesting find

[SteveB]

There is much that is really conjecture in geology. We don’t directly observe the formation processes but we get some evidence as we mine deeper. We can also gain some insight from the “experimental results” of manufactured quartz crystals. Its also often the case we look at something and think “this is its final state” when we are really looking at where the process ended for this specimen which is not the destination if the process had been allowed to continue. Eg as temperature changed, as the solution it formed in weakened or drained away .

Interesting thoughts though but I dont think you’re on the right track there with it. A number of those specimens appear to be longer crystals that got broken in half, perhaps as the cooling ground around them shrunk and cracked as it solified. That held the two parts in position in relation to each other as the potentially millions of tons of rock around them moved by a small amount. This crack could have allowed more solution to fill the void and a new crsystal started to form between the two halves joining them.

The melted ones I think were more a change in the solution itself. Melt rock to a liquid and heavier elements will still gravitate towards the bottom of the liquid over time, lighter to the top, so like taking a jar of water and adding a handful of dirt and shaking it up, the entire solution is not 100% identical at every point in the solution or over time. Time I think is the hard part to imagine. Itseasy to pick up a specimen and think it formed like this and has been waiting in the ground for us to come along and find it. It may have taken a vast amount of time to first form in the right conditions but over time the conditions change and formation struggled, faltered and stopped,. But this process could also be repeated if conditions come back to restart formation or even start a new different formation. So I think these “melted” examples are more likely to be a transitional phase in the specimens growth.

These thoughts can be tested by analysing samples of a specimen at different positions and depths in the specimen to determine the precise chemical composition of each specimen itself. Knowing precisely where the specimens were found can give some indication as to possible transitions to other minerals also found at the location. We may never know for certain exactly how a specimen formed but we should be able to reproduce similar formations and this may hint at the original processes. It wont prove them but will demonstrate one combination of factors that end up at a given end point.

You can observe a variety of differences yourself making copper sulfate crystals. I grew batches in icecream containers. The crystals inside the solution that formed would be self similar: same shape geometry and colour, different sizes, not just one giant crsyatl or a hundred small ones but a variety of both. Clusters could form and somtimes where two formed next to each other or just grew large they could become unbalanced and shift position, causing some finer specimens to crack and break and also reform differently. Around the top of the container where it was open to the air the edge of solution would form a different structure of “melted” oxidised whitish formations (but i didnt leave the solution to continue until this layer met the growing crystals ). Also I noticed there would be a sludge in the bottom of the solution around the growing crystals. Sometimes this would interfere with the crystal growth, stunting its growth in one or more directions. This sludge I put down to impurities in my source copper sulfate and the tap water. Point being this is a simple enough experiment to try at home and just observe the results for yourself, Usually we are wanting nice clear blue crystals from this but take a small crystal out of he solution and sit it on a tissue and it will start to eventually grow the whitish crust as air and humidty reacts with the surface. And it all happens over long time, but it helps give an appreciation of how long term conditions can effect mineral growth and how weird and wacky formations can be found, not everything forms perfectly the same with the same solution.

[Reef]

[marco campos-venuti]

I Have more doubly terminated Scepters.

[Reef]

As you can see, my scepter is not alone. How often do such creations occur?

[marco campos-venuti]

I found also some scepters in other minerals. True scepters, not etched.