Isua Banded Iron — Ventifact-Shaped, Greenland [140 g ~ 3.7 Ga]
Brand : Jensan Scientifics LLC
- SKU:
- JPT-92175
- Condition:
- New
- Availability:
- Usually ships in 24 hours.
- Weight:
- 1.00 LBS
- Minimum Purchase:
- 1 unit
- Maximum Purchase:
- 1 unit
- Shipping:
- Calculated at Checkout
Isua Banded Iron Formation, Greenland
This banded iron formation specimen came from Greenland's Isua Greenstone Belt, where about 3.7-billion-year-old magnetite preserves Earth's magnetic field from that time. This is the oldest known record of Earth's magnetic field. It shows that a protective magnetic shield already surrounded the planet while early life was getting started.
About This Isua Banded Iron
Banded iron formations are layered rocks made of alternating iron-rich and silica-rich bands. They formed when iron dissolved in oxygen-poor seawater settled to the seafloor, layer by layer, long before plants, animals, or an oxygen-rich atmosphere existed.
This 140-gram specimen stands out for its shape. Its ventifact-like look comes from its natural, angular, tiered form, like a weathered stone figure. Each side shows something different:
- Front: silvery magnetite layers with bold, rhythmic banding
- Back: darker, magnetite-rich planes with fine linear veining
- Sides: crisp alternating iron-rich and silica-rich layers
Product Information
| Object | Isua banded iron formation specimen |
| Material | Magnetite and quartz (silica) banded iron formation |
| Geologic Age | Eoarchean, ~3.7 Ga |
| Source Region | Isua Greenstone Belt, southwest Greenland |
| Preparation | Natural form with one diamond-lapped face polished smooth |
| Dimensions and Weight | 90 mm L x 70 mm W x 31 mm D, 140 grams |
| Photographic Notes | Photographed from the front, back, and both sides to show the specimen's full angular, tiered form |
| Science Gift Options | A commanding gift for collectors of deep-time geology, educators, and anyone fascinated by early Earth, with a free science poster |
| What's Included | Specimen, Certificate of Authenticity (COA), Isua Greenstone Belt information sheet, specimen tag, tag stand, free science poster. Specimen stand and photo cube not included. |
| Provenance and Authenticity | All of our material is proprietary and sourced from scientists and/or verified scientific estate collections, backed by the included Certificate of Authenticity. |
| Legality | Professionally and legally collected; from a proprietary scientific estate collection |
| Brand | Jensan Scientifics / Sciencemall-USA |
| SKU | JPT-92175 |
| Availability | ONLY 1 unique, ventifact-shaped specimen available |
Images professionally photographed under controlled studio lighting using Zeiss optics and a pro-grade Canon camera, for guaranteed accuracy. The brass scale cube measures 1 cm per side.
Rarity and Significance
| Geologic Age | ★★★★★ |
| Scientific Importance | ★★★★★ |
| Availability to Collectors | ★☆☆☆☆ |
| Research and Teaching Value | ★★★★★ |
| Display Presence | ★★★★★ |
Questions Commonly Asked About Isua Banded Iron
Does Isua banded iron record Earth's early magnetic field?
Yes. When the magnetite in these rocks formed, it locked in the direction and strength of Earth's magnetic field at that moment, like a natural compass frozen in stone. A 2024 study of Isua banded iron found a magnetic field about 3.7 billion years ago with a strength of at least 15 microtesla, roughly half of today's field.
This is the oldest known record of Earth's magnetic field. It shows that a protective magnetic shield surrounded the planet as early life began.
Does magnetite or the whole rock record Earth's magnetic field?
It is the magnetite. Magnetite grains act as tiny natural magnets; when they formed, they lined up with Earth's magnetic field and stayed aligned. The pale quartz bands carry no magnetic signal. The banded iron formation is the rock that holds the record, but the magnetite is what records it.
You can test this yourself: a small magnet will be attracted to the dark, iron-rich bands of this specimen, not the pale ones.
What is a banded iron formation?
A banded iron formation is a sedimentary rock built from thin, alternating layers of iron minerals and silica. In Earth's early oceans, iron dissolved freely in oxygen-poor seawater. When some of that iron oxidized, it settled to the seafloor as iron-rich layers that alternated with silica layers. Over billions of years, heat and pressure turned the iron into magnetite and the silica into quartz.
Why is Isua so important to scientists?
The Isua Greenstone Belt, also called the Isua Supracrustal Belt, contains some of Earth's oldest rocks that formed at the surface, on the seafloor, and in ancient volcanoes. Because so little crust from this time survives, Isua is one of the few places where scientists can study what Earth's oceans, crust, and earliest environments were like about 3.7 billion years ago.
Is this specimen a true ventifact?
No. A true ventifact is a rock shaped by wind-blown sand, usually in deserts or cold, windy regions. This specimen only resembles one. Its ventifact-like shape comes from its natural, angular, tiered form, like a weathered stone figure. A single diamond-lapped face is polished smooth to clearly show the banding.
How is the age known?
Volcanic rocks layered within the Isua Greenstone Belt contain tiny zircon crystals. The steady decay of uranium to lead inside these crystals acts as a natural clock, dating these rocks to about 3.7 billion years old.
Isua Banded Iron is the oldest known record of Earth's magnetic field.
This one-of-a-kind Isua banded iron specimen captured Earth's early magnetic field ~3.7 Ga. With its natural, angular, tiered form and bold Archean banding, it is both a scientific time capsule and an intriguing display piece.
