Hennie Kruger and a few interesting snaps!

[Michael Alexander]

Here are a few interesting snaps from Hennie Kruger, The one of note is the one about the gas bubble caught in stone,that had the following caption.

"I am lead to believe that this is a gas bubble trapped in stone , and
the crystal grew inside the holow over many milenia .
This is from the " Buntfelshun " area
I would like to hear from our Geologists what they say  about it"

[Michael Alexander]

Sorry Hennie,  I forgot the captions....

Guys and Gals, the one with the fern on the rock has the following caption..

"I am of the opinion that the fern like patrens are the result of
"impurities " rather than fosils
Can a geologist please explain what it is ?
This is from Swartkops Area . CDM"

[Paul (Pepe) Freemantle]

Mike and Hennie, the photo of the gas bubble trapped in stone is actually called a desert rose. When I was still out at Baker's Bay erecting the sampling plant we picked up many there. I used to take them to Cape Town and sell them to a jeweler in the Gardens Center also called The Desert Rose, funny how that worked out.

[Gordon Brown]

Mike you are quite right about the fern-like patterns. This is most probably Psilomelane, a hydrous barium manganese oxide. The fern-like variety is called dendritic psilomelane. It forms in the oxidation zone of manganese oxide and silicate deposits, usually sedimentary, also on the bedding or fracture planes of many limestones.
Kind regards, Gordon.

[Michael Alexander]

Thanks Gordon, It was Hennie who reckoned it was a result of impurities....

[henniek]

Paul , thankyou for your comment about desert roses that you got from Bakers , I always heard people talk about the Desert Rose , and I assumed that they refer to the sand rose.  I attach a pic of Sand Roses, Black , Grey and brown.
As John creedy said , The power of this site is wonderful .
Gordon I had these stones weith the paterns for may years , Always wondering what caused the brown markings , And you readely supplied the answer ! Thanks

[Michael Alexander]

Nice specimens of desert Rose's!

[Gordon Brown]

Hennie, the first mineral is most likely a Geode, which is a hollow, globular body varying in size from 25mm to 300mm. These are characteristic of limestone beds and significant features are 1. subspherical shape 2. a hollow interior 3. a clay film between the geode wall and the enclosing limestone matrix 4. an outer chalcedonic layer 5. an interior drusy lining of inward projecting crystals and 6. evidence of expansion or growth.
The inner mineral is Desert Rose (gypsum) as Paul correctly identified.
Kind regards
Gordon

[Clint Ebstein]

The crystal is a desert rose and the inside was filled with a lighter sand(gypsum) enclosed by fossilized clay. Salt water seeped in and the crystal started growing.

[Alfred Boehme]

Here are a few interesting snaps from Hennie Kruger, The one of note is the one about the gas bubble caught in stone,that had the following caption.

"I am lead to believe that this is a gas bubble trapped in stone , and
the crystal grew inside the holow over many milenia .
This is from the " Buntfelshun " area
I would like to hear from our Geologists what they say  about it"

the runes of the desalination plant is stil there got a pic some where will get it posted

[Clint Ebstein]

Attached are the big balls from Buntfeldschuh which are solid inside

[Gordon Brown]

South of Bogenfels the country consists of north-south rock ridges with salt pans on the coast, of which Angras Juntas and Marmora are but two. About 6.5 kilometres inland from Angras Juntas is the prominent escarpment of Buntfeldschuh (elevation 200 metres). It varies from 30 to 50 metres in height above the coastal plain and is composed of greenish sand and silts with chalcedonic nodules; these are bands of well-sorted pebbles consisting of agates, jasper and yellow chalcedony. The escarpment has a capping of calcrete though this changes to ferricrete at the south end (Kakaoberg).

[Gordon Brown]

Nice pics Clint.
Hope to see dad at Sea Point Pavillion this summer.
Kind regards
Gordon

[henniek]

Thank you all , this is very interesting to get all the facts about the desert roses etc
attached a pic of black - looks like petrified shark teeth from 2 plant

[Alfred Boehme]

Desalination pic's this is what is left