AGAMS Monthly Geology News – June 2026
Welcome to the June edition of the AGAMS Monthly Geology News! This month we explore
a rare color-changing gemstone, a beautifully preserved fossil fern, and exciting
Earth science discoveries from around the world.
Mineral of the Month — Alexandrite
Alexandrite is a rare and remarkable variety of chrysoberyl known for its dramatic
color-change effect. In daylight, it appears green to bluish-green, but under incandescent
light it shifts to red or purplish-red. This optical phenomenon, often called the
“alexandrite effect,” is caused by trace amounts of chromium in the crystal structure.
Image courtesy of the Smithsonian Institution, via Wikimedia Commons, used under CC BY 4.0.
- Chemical Formula: BeAl2O4 (chrysoberyl)
- Color: Green in daylight; red to purplish-red in incandescent light
- Hardness: 8.5 on the Mohs scale
- Crystal System: Orthorhombic
- Notable Localities: Russia (Urals), Sri Lanka, Brazil, East Africa
- Special Feature: Strong color change due to chromium absorption bands
Theme: “Emerald by day, ruby by night — the magic of Alexandrite.”
Fossil of the Month — Fern Fossil (McGraths Flat)
This beautifully preserved fern pinnule fossil comes from McGraths Flat, a Miocene-age
rainforest in New South Wales, Australia. The site is known for exceptional preservation
in iron-rich rock, capturing microscopic details rarely seen in fossils.
Image used under CC BY 4.0 from the McGraths Flat fossil research collection.
- Age: 11–16 million years (Miocene)
- Location: New South Wales, Australia
- Environment: Lush rainforest with lakes and wetlands
- Preservation: Iron-rich goethite captures microscopic detail
- Why It Matters: Offers a rare look at ancient Australian ecosystems and climate change
Theme: “A rainforest frozen in iron — the Miocene world of McGraths Flat.”
Earth Science News
This month we highlight three exciting new discoveries from the world of geology and Earth science, all published within the last three months.
1. USGS and NASA map critical minerals from 65,000 feet
USGS and NASA expanded the world’s largest airborne hyperspectral survey, using high-altitude aircraft to map critical mineral deposits across the United States. This project helps identify future sources of rare-earth elements needed for electronics and renewable energy. Read more
2. Ancient lake may have helped carve the Grand Canyon
A new USGS-led study found evidence that a massive prehistoric lake spilled over and contributed to the early carving of the Grand Canyon. The findings support the idea that catastrophic flooding played a major role in shaping the canyon’s earliest form. Read more
3. The Wrekin Ruby: Britain’s Most Infamous Gemstone Fraud
The story of the Wrekin Ruby stands as one of the most audacious gemstone valuation frauds in UK business history. This case reveals how creative accounting, forged certificates, and an inflated gemstone valuation brought down a construction company and cost 530 people their jobs.. Read more
June Theme: New tools, new minerals, and new clues to Earth’s ancient past.
Kids Corner — June Activity
June Theme: Color-Changing Gems and Fossil Impressions!
Activity 1: Make Your Own Color-Changing Gem
You’ll need: Colored cellophane, tape, flashlight
- Layer two colors of cellophane to make your “gem.”
- Hold it up to daylight and observe the color.
- Shine a flashlight through it — does the color change?
Activity 2: Create a Fossil Impression
You’ll need: Clay or play-dough, a leaf or small fern
- Flatten your clay.
- Press the leaf firmly into the surface.
- Lift it up to reveal your fossil impression.
Fun Facts
- Alexandrite can appear green or red depending on the light.
- Real fern fossils can be millions of years old.
- Some fossils show tiny details like leaf veins.
Vocabulary
- Gemstone: A mineral that can be cut and polished.
- Fossil: Preserved remains or impressions of ancient life.
- Impression: A shape left behind when something presses into soft material.
- Color Change: When something looks different depending on the light.
Upcoming Events
- June 19: Monthly AGAMS Meeting