Meteorites

Fragments of the Solar System

• Dedicated to Dr. Elbert King – First director of the Lunar Receiving Lab – Recovered a lot of Allende!!

– Meteoriticist

Meteorites • Meteoroids – “small” rocks orbiting in space • Meteors – “rocks” entering the atmosphere and glowing – Most are the size of a grain of sand – Some are a lot bigger!!!

• Meteorites – Rocks from space that have hit the Earth

Thunderstone of Ensisheim • 1492

Thunderstone of Ensisheim What’s left of it

• What Holbrook supposedly looked like 1946

• Famous painting of the Shikote-Alin meteorite on a USSR postage stamp.

Meteorites • • •

Irons

iron + nickel

Stoney Irons

– Mesosiderites MES silicate + iron – Pallasites PAL iron + silicate (olivine)

Stoney

– Chondrites silicate + some iron (sometimes) • Ordinary Chondrites H, L, LL • Carbonaceous Chondrites C, CO, CV, CM, CK • Others – Enstatite Chondrites E – Rumruti R – Achondrites • HED – from Vesta • SNC – from Mars • ALUN – from the Moon

Irons • Cape York – “discovered” by Peary from Greenland actually discovered by local Inuit

Irons

Irons

Irons • Witmanstatten Patterns • Gibeon

• Willamette Irons

• Irons Hoba – 60 tons • Campo del Cielo

Stony Irons • Mesosiderites - MES • Silicate based – with a lot of metal running through it.

• NWA1879

• Another mesosiderite -MES Stoney Irons

Stoney Irons • Mesosiderite Morristown

Stoney Iron • Pallasites • Iron based – with olivine crystals sprinkled through • Thought to be from the core mantle boundary of the parent asteroid

Stoney Iron

Pallasite – lit from behind

Stoney - Chondrites • Ordinary Chondrites – H (High Metal) – L (Low Metal) – LL (Very Low Metal) • Inside (Brecciated) Outside (Crusted) Probably a L4-5 – this comes from NWA – Morocco

Chondrules / Chondrites

Stoney - Chondrites • Carbonaceous chondrites – Residue from the formation of the Solar System – 4.5+ Billion Years old Murcheson – CM2 Allende – CV3.2

Stoney - Achondrites Meteorites from Asteroid 4 Vesta • HED Howardite • DAG 844

Stoney - Achondrites • HED Eucrite • Millbillillie

Stoney - Achondrites • HED Diogenite • Johnstown

Stoney - Achondrites Meteorites from Mars • SNC Shergottite • Zagami

• SNC Stoney - Achondrites DAG 476 Dhofar 019

• ALUN Stoney - Achondrites Meteorites from the Moon • DAG 400

• • • How do we know they are from Mars / the Moon / 4 Vesta??

Mars

: Viking 1 and 2 had soil and atmosphere analyzers. The percentages of the elements and isotopes are the same as the SNC meteorites – and different from others!

The Moon

: Same story – except we have real moon rocks to compare them to

Vesta

: Spectroscopy of Vesta indicates it is made of HED materials, and no other asteroid is. Recent studies show a great crater on Vesta where some of these materials must have been ejected from.

How to Study Meteorites • What does it look like (big picture) • What does it look like (microscope) • What elements are in it (chemistry and microprobe) • What isotopic ratios are there (microprobe) • Where did it come from (compare to asteroids and planets) • How did it fall (distribution)

Meteorites / Meteorwrongs • Meteorites are not hot when they hit the earth!

• Almost all meteorites are magnetic!

• Almost all meteorites have some visible metal (though sometimes only a little).

• Most meteorites are denser than local rocks.

• Meteorites don’t have holes/bubbles in them.

• For real analysis you have to take it to an expert

How to Study Meteorites • Thin Sections – The coolest way to look at meteorites is in “thin section”. Take a thin slice of the rock, glue it to a microscope slide and grind/polish it until it is 30 micrometers thick.

You can then look at it under a “petrographic microscope” with crossed polarizing filters. The colors tell you the minerals!

Eucrite Enstatite

Richfield LL3.7

Pultusk

• SNC

Some chondrules in thin section

Eucrite thin section • Looks a lot like Kilauea basalts!

Apollo 17 Basalt

Apollo 12 Basalt

Impact!!!

• When a Big rock hits – 50 meters or more – it can make a rather big hole in the ground!!!!

Meteor Crater

Wolf Creek

Lake Manicoagan

Chixilub

Brent Crater

Pretoria “Saltpan”

Sudbury + Lake Wanapitei

Disclaimer Aloha I put together these power points for use in my science classes.

You may use them in your classes.

Some images are public domain, some are used under the fair-use provisions of the copyright law, some are mine. Copyright is retained by the owners!

Ted Brattstrom