In this quick and inexpensive tutorial, we are going to show you how to make an Outrageous Opal Expedition. These excavations are super easy to make and are a great teaching resource to include in your next lesson or discussion about opals, gemstones, geology, and more.


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Plaster of Paris


Mixing Bowl

Wooden spoon

Measuring cups

Popsicle sticks – Popsicle sticks are inexpensive, readily available, and make great excavation tools.

Safety goggles or glasses – You we need to provide or borrow a set for each student.

Optional – Brushes and magnifying glasses.

Empty Altoids Tin

Rough opals - There are many varieties of opals and you can easily find inexpensive bags of rough opals online to use in this excavation activity. 


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  1. Place some opals in the tin. If the opals are too large, place a few in an old sock and while wearing safety goggles, gently tap the opals. Opals are brittle and will easily break. Dispose of the sock as the little shards of opal are very sharp. 
  2. Mix 1 cups sand with 1/3 cup Plaster of Paris.
  3. Add 1/3 cup of water and mix until you have a pancake batter consistency.
  4. Pour the mixture over the opals.
  5. Place the Outrageous Opal Expedition in front of a fan overnight until it is completely dry.
  6. Distribute the excavation, excavation tools, and safety goggles to your Excavating Adventurer and have fun watching them dig in and discover the awesome opals you have hidden inside.


Opal Delights: Shimmering Rainbows and Magical Stones!

Fun Facts about Opal:

  1. Opal is a gemstone known for its mesmerizing play of colors, displaying a spectrum of hues that can resemble a shimmering rainbow.

  2. It is formed from silica gel that seeps into cracks and crevices, and over time, hardens to create the unique patterns and colors seen in opals.

  3. Opal can come in various color variations, including white, black, blue, green, and even fire opals with vivid red, orange, and yellow tones.

  4. Opals are one of the few gemstones that are not classified using the Mohs hardness scale. Instead, they are classified based on their ability to take and retain a polish.

  5. Opal is often associated with imagination, creativity, and inspiration, and has been considered a symbol of hope, luck, and magic.

  6. Australia is the world's primary source of opals, with around 95% of all opals coming from the Australian outback.

  7. Opals are made up of small silica spheres that diffract light, creating the play of colors known as opalescence.

  8. Lightning Ridge in Australia is renowned for producing black opals, which are highly valued for their dark body tone and vibrant play of colors.

  9. Opals can display a phenomenon called "pinfire" or "flash," where small, bright dots or flashes of color appear within the stone.

  10. Opals are delicate gemstones and require gentle care to prevent them from cracking or drying out. They should be protected from extreme temperature changes and harsh chemicals.

  11. The word "opal" is derived from the Latin word "opalus," which means "precious stone."

  12. Opals have been cherished for centuries, and they have been used in jewelry and as ornamental stones to create exquisite and unique pieces.

Remember, opals are like magical portals to a world of vibrant colors and captivating beauty, ready to ignite your imagination and fill your heart with wonder!



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Question 1: Where is the primary source of opals in the world? A) Brazil B) Australia C) South Africa D) India

Correct answer: B) Australia

Question 2: What gives opals their unique play of colors? A) Inclusion of metallic elements B) Refractive index C) Chatoyancy effect D) Diffraction of light

Correct answer: D) Diffraction of light

Question 3: Which term describes the small, bright dots or flashes of color within an opal? A) Luminescence B) Iridescence C) Opalescence D) Pinfire

Correct answer: D) Pinfire