L'agate du Montana est considérée comme une agate mousse en raison de la forme de ses inclusions, mais on trouve également des inclusions rubanées à pois ou a des dendrites. La majeure partie des agates du Montana brutes sont brisées et trouvées en plus petits morceaux. Les morceaux de plus de 5kg sont rares. Cependant, le plus gros morceau jamais trouvé pesait 30kg  ! L'agate du Montana est un quartz microcristallin et a une dureté de 7, ce qui rend les cabochons de designer très portables.L'agate du Montana est la gemme officielle de l'État du Montana (avec le saphir du Montana) depuis 1969.

 

Fiche d'identité :

Agate var. Montana

Calcédoine rubanée

Taillée en Californie par un lapidaire indépendant

Origine : Montana USA

27,59 carats environ

20 mm env. grande et 15mm env. les 2 petites

Naturelle

 

English :

It comes from near the Yellowstone River.

Montana Agate is one of the alluvial agates, it is not found in-site, but in the Flaxville gravel deposits scattered over a huge area encompassing thousands of square miles. Montana Moss Agate is found throughout the 670 mile length of the river.

The agate originally was formed in the Yellowstone National Park area of Wyoming as a result of volcanic activity approximately 65 million years ago.

In Montana Agate cabochons the red color is the result of iron oxide, the black and brown is the result of manganese oxide and the red and orange came from iron oxide. On very rare occasions you can get a green from copper. 

It is considered a moss agate because of the mossy shape of its inclusions, but more often it is banded, polka dotted or has dendrites.

Most of the Montana Agate rough is broken up and found in smaller pieces.  Chunks larger than 10 pounds are rare.  However the largest piece ever found weighed 63.5 pounds! 

Montana Agate generally has a coating or skin.

Agate is a microcrystalline Quartz and has a hardness of 7, which makes the Montana Agate designer cabochons very wearable.

Montana Agate has been the state of Montana's official state gemstone (along with Montana Sapphire) since 1969.

Agates du Montana - Set de 3 pierres - 27,59 carats - USA

SKU : AGMON1
70,00 €Prix