Opal Belemnites - From Animal To Gemstone

Procesando...

[Read Time: 5 Minutes]

Every serious opal enthusiast wants to have an opalized belemnite fossil in their opal collection. Belemnites are ancient Cephalopods from around 100 million years ago. Most opalized belemnites are found only in the South Australian opal fields around Cooper Pedy. Ancient cephalopods were squid like creatures that are related to the Octopus and Cuttlefish.

Summary

Belemnite are ancient sea creatures
Once deceased they leave a cavity in the clay which is filled with Opal
The most famous Belemnite is the Virgin Rainbow

What Are Belemnites

Belemnites are found in many countries including Sweden, England, Morocco and the USA. These creatures were prolific swimmers and vast quantities existed on earth but only Australian belemnites from Cooper Pedy are opalized. Beleminte fossils can be found in host rock all around the world. However in Australia the cavities left behind byu the Belemnite was filled with Opal instead of other material such as Quartz. This is why Australia is the only place in the world where Opalized Belemnites are found.

This make them a must have for opal enthusiasts. But they are very rare and to find one with full opal colour is very expensive. A torpedo shaped belemnite with translucent opals colours spectrum are extremely expensive. Most of the time they are found broken into pieces. Broken belemnites with clear or light sea blue colours are still reasonable priced.

Other ancient Cephalopoda include other molluscs such as

Octopuses
cuttlefish
nautilus

If you find a parcel of rough opal make sure you look for these. Octopus is extremely rare but there have been some findings in the past.

Belemnites were different to modern day squids as they had internal skeleton and no tentacles like modern squid. They had ten arms with studded hooks instead tentacles. In scientific community they are called Belemnitida (genus) belemnites, extinct cephalopods from Mesozoic to upper cretaceous era. Belemnoids were squids but more closely resembled the cuttlefish.

The World’s Most Famous Belemnite is The Virgin Rainbow

A 72 carat Black Crystal Opal belemnite fossil found in 2003. This opal is on display at Adelaide Museum celebrating 100 years of opal mining in the state. The exhibition is called simply OPALS.

Also on display is a six-meter Plesiosaurus that has an opalescent sheen in its skeleton.

South Australia was once under sea water in prehistoric times which was filled with marine creatures like aquatic reptiles. The director of the museum is excited to show opals that were formed when South Australia was under the sea and dinosaurs walked the planet. Compared to the famous opal mines at Lighting Ridge in New South Wales which were fresh water rivers and swamps so different prehistoric species are found in this area like mussel’s shells, pine cones etc.

The specimen pictured above is in the Seda Opals collection and consists of two belemnites a rare black crystal opal and a rare multi fire crystal opal.

How Does A Belemnite Become Opalized?

When a belemnite died it would sink to the bottom of the sea and the sediment on the floor would be very muddy from the clay based soils. The decaying body would have been covered in this clay sediment very rapidly and stayed there for millions of years in desert type conditions.

After the sea eventually dried up the acidity in the sandstone soil greatly increased and the silica gel from the sandstone escaped and filled in crevices in the clay and in some areas these belemnites were encased in clay.

Over millions of years the acidic levels dropped and the silica gel hardened into opal in impressions of the decayed squid. This process was not common and most belemnites do not have opal colours. It is extremely rare to find multi colour opal or black crystal opal like the virgin rainbow.

It is understanding the rarity of this opal that makes one appreciate how rare and unique it is for mother nature to have produced such a spectacular belemnite opal

What Are Opal Pipes

Opal pipes should not be confused with Belemnites. They are cylindrical shaped not torpedo shape and are found in many opal fields. They are formed in ironstone/sandstone potch.

These crystal pipes can be small only 1-2 mm wide or up to 12mm diameter and can be hollow or filled. These tubes are known as breccia pipes. Theory is that the hollow tubes had water running through them when formed and there is no relationship with prehistoric animals. Many opal pipes are cut into boulder crystal stones and sold with realizing that they were pipe opal.

Shop For Belemnites

Belemnite Fossils

[Tiempo de lectura: 5 minutos]

Todo entusiasta de ópalo serio quiere tener un fósil de belemnita opalizado en su colección de ópalo. Los belemnitas son antiguos cefalópodos de hace unos 100 millones de años. La mayoría de las belemnitas opalizadas se encuentran solo en los campos de ópalo del sur de Australia alrededor de Cooper Pedy. Los cefalópodos antiguos eran calamares como criaturas relacionadas con el pulpo y la sepia.

Resumen

Belemnite son criaturas marinas antiguas
Una vez fallecidos, dejan una cavidad en la arcilla que está llena de ópalo.
El belemnita más famoso es el arcoiris virgen

La belemnita más famosa del mundo es The Virgin Rainbow

Un fósil de belemnita de ópalo de cristal negro de 72 quilates encontrado en 2003. Este ópalo se exhibe en el Museo de Adelaida para celebrar los 100 años de extracción de ópalo en el estado. La exposición se llama simplemente OPALS.

También se exhibe un Plesiosaurus de seis metros que tiene un brillo opalescente en su esqueleto.

Australia del Sur estuvo una vez bajo el agua del mar en tiempos prehistóricos que estaba llena de criaturas marinas como reptiles acuáticos. El director del museo está emocionado de mostrar ópalos que se formaron cuando Australia del Sur estaba bajo el mar y los dinosaurios caminaron por el planeta. En comparación con las famosas minas de ópalo en Lighting Ridge en Nueva Gales del Sur, que eran ríos y pantanos de agua dulce, se encuentran diferentes especies prehistóricas en esta área, como conchas de mejillones, conos de pino, etc.

El espécimen que se muestra arriba está en la colección Seda Opals y consta de dos belemnitas, un raro ópalo de cristal negro y un raro ópalo de cristal de fuego múltiple.

¿Cómo se opacifica una belemnita?

Cuando una belemnita murió, se hundiría en el fondo del mar y el sedimento en el suelo estaría muy embarrado por los suelos arcillosos. El cuerpo en descomposición se habría cubierto con este sedimento de arcilla muy rápidamente y habría permanecido allí durante millones de años en condiciones de tipo desértico.

Después de que el mar finalmente se secó, la acidez en el suelo de arenisca aumentó enormemente y el gel de sílice de la arenisca escapó y rellenó grietas en la arcilla y en algunas áreas estas belemnitas se encerraron en arcilla.

Durante millones de años, los niveles de ácido disminuyeron y el gel de sílice se endureció hasta convertirse en ópalo en impresiones del calamar podrido. Este proceso no era común y la mayoría de las belemnitas no tienen colores opal. Es extremadamente raro encontrar ópalo multicolor o cristal negro como el arcoiris virgen.

Es la comprensión de la rareza de este ópalo lo que hace que uno aprecie lo raro y único que es para la madre naturaleza haber producido un ópalo belemnita tan espectacular.

¿Qué son los tubos de ópalo?

Las pipas de ópalo no deben confundirse con las belemnitas. Tienen forma cilíndrica, no forma de torpedo y se encuentran en muchos campos de ópalo. Se forman en potch de piedra arenisca / arenisca.

Estos tubos de cristal pueden ser pequeños de solo 1-2 mm de ancho o hasta 12 mm de diámetro y pueden ser huecos o rellenos. Estos tubos se conocen como tubos de brecha. La teoría es que los tubos huecos tenían agua corriendo a través de ellos cuando se formaron y no hay relación con animales prehistóricos. Muchos tubos de ópalo se cortan en piedras de cristal de roca y se venden al darse cuenta de que eran tubos de ópalo.