Meteorites 101: Did Your Rock Really Come From Space?

Meteorites are pieces of asteroids, the Moon or Mars that survived a fiery trip through our atmosphere. They are rare, and collectors call the many look-alikes "meteor-wrongs". Here is a simple checklist to start with.

Clues that point toward a meteorite

• Fusion crust. A thin, dark, often matte skin formed as the outer surface melted during entry.
• Heavy for its size. Many meteorites contain iron–nickel metal and feel denser than ordinary rocks.
• Attracted to a magnet. Most meteorites contain some metal, so a strong magnet will usually stick or pull.
• Thumbprint-like dents called regmaglypts, especially on iron meteorites.

Clues that point away

• Bubbles or holes are typical of volcanic rock or industrial slag, not meteorites.
• A red-brown or black streak on unglazed ceramic often means hematite or magnetite, two common look-alikes.
• Layers or visible crystals of quartz point to an Earth rock.

Next steps

If your stone passes the first tests, many universities and natural history museums offer identification services. A confirmed meteorite can be classified and, in some cases, officially named. When you post on MARSMALL, tell the community how you tested it — the conversation is half the fun.