Don’t Throw Away that Hot Rock!

Attention metalElement that readily forms cations and has metallic bonds; sometimes said to be similar to a cation in a cloud of electrons. The metals are one of the three groups of elements as distinguished by their ionization and bonding properties, along with the metalloids and nonmetals. A diagonal line drawn detectorists and treasure/relic hunters! STOP!!!

Don’t throw away any hot rocks until you check and verify they are not meteorites. Meteorites are another kind of treasure you may encounter during your search.

Those of you who hunt gold nuggets and relics in the deserts of the southwest, Alaska, or anywhere for that matter have run across pesky hot rocks. These are highly mineralized rocks that make your metal detectorAny device used to sense the passage of a particle or photon (x-ray, γ-ray, etc.). X-rays can be detected using sealed-gas proportional, gas-flow proportional detectors, and Li-drifted Si semiconductor detectors. A Li-drifted Ge detector is used to count γ-rays in the laboratory. sound off and make you think you found something good, even if only for a moment. Nugget-shooters, metal detectorists, and relic hunters have all kicked, thrown, or tossed hot rocks in the bushes at one time or another. It’s something that for most hunters is an everyday annoyance.

MeteoriteWork in progress. A solid natural object reaching a planet’s surface from interplanetary space. Solid portion of a meteoroid that survives its fall to Earth, or some other body. Meteorites are classified as stony meteorites, iron meteorites, and stony-iron meteorites. These groups are further divided according to their mineralogy and hunters on the other hand, check the bushes, rock cairns and old dig holes (by the way; shame on anyone who doesn’t fill their dig holes!) for hot rocks that might be a meteorite; meteorites you may have inadvertently thrown aside and left for someone else to findMeteorite not seen to fall, but recovered at some later date. For example, many finds from Antarctica fell 10,000 to 700,000 years ago..

Stone Meteorites may not look like anything special. But they will make your detector sound off and many a hunter has been fooled into thinking it was nothing more than a hot rock. Gold detectors are particularly useful in finding meteorites. Their extreme sensitivity that makes them good for gold nugget hunting, also makes them very sensitive to the iron content in meteorites. You simply don’t use discrimination. Stone meteorites contain a high percentage of nickel iron, higher than nearly any other Earth rock (one notable exception is AwaruiteNi-rich Fe metal, Ni3Fe, similar to taenite found in minor amounts in some meteorites. Awaruite is also known as josephinite, a mineral found as placer deposits in Josephine County, Oregon, and sometimes mistaken for a meteorite. Note: web.mineral.com incorrectly defines Awaruite as “Ni2Fe to Ni3Fe”, however the IMA Database of also known as Josephenite). These stony meteorites will set off the detector and will sound similar to a “Leavertite” hot rock. Iron meteorites are a bit more obvious and can easily be identified as an uncommon rock in the field.

It’s important to be able to identify a meteorite while in the field. There are a number of field ID methods and certain characteristics of meteorites you should be on the lookout for.

• Magnetic: Because most meteorites have iron in them, this makes them magnetically susceptible. Keep in mind there are MANY earth rocks that will attract a magnet as well. Just because a rock is magnetically susceptible, does NOT mean it’s a meteorite. In fact, it is more likely to be HematiteFe-oxide mineral (Fe2O3) that may be the major cause of the red color on Mars. Coarser-grained gray hematite has the same chemical formula as the red variety, but a different crystalline structure. Deposits of gray hematite found in the Terra Meridiani region of Mars may suggest that water once circulated or MagnetiteFe oxide, Fe²⁺Fe³⁺2O4, containing oxidized iron (Fe³⁺) found in the matrix of carbonaceous chondrites and as diagnostic component in CK chondrites. In CK chondrites, magnetite is typically chromian, containing several wt. % Cr2O3.. However, using a magnet is just the first step to identifying a rock as a potential meteorite. So, keep a rare earth magnet handy to test your hot rocks. Some meteorites will only slightly attract the magnet.
• Heavy and/or Dense: Meteorites tend to be heavier than most Earth rocks both due to densityMass of an object divided by its volume. Density is a characteristic property of a substance (rock vs. ice, e.g.). Some substances (like gases) are easily compressible and have different densities depending on how much pressure is exerted upon them. The Sun is composed of compressible gases and is much and iron content.
• Fusion CrustMelted exterior of a meteorite that forms when it passes through Earth’s atmosphere. Friction with the air will raise a meteorite’s surface temperature upwards of  4800 K (8180 °F) and will melt (ablate) the surface minerals and flow backwards over the surface as shown in the Lafayette meteorite photograph below.: Meteorites enter our atmosphere at thousands of miles per hour on a fiery course towards Earth’s surface. This causes the meteorite to have a burned look. It’s actually a glassy like thin melt crustOutermost layer of a differentiated planet, asteroid or moon, usually consisting of silicate rock and extending no more than 10s of km from the surface. The term is also applied to icy bodies, in which case it is composed of ices, frozen gases, and accumulated meteoritic material. On Earth, the on the outside of the stone, and will look like a charcoal briquette on freshly fallen meteorites. Older meteorites which have been weathering for hundreds or thousands of years could have residual fusionProcess in which two lighter atomic nuclei combine to form a heavier atomic nucleus. Very high temperatures are normally required in order for atomic nuclei to collide with sufficient energy to overcome the Coulomb barrier (their mutual electrostatic repulsions). Fusion that occurs under high-temperature conditions is called thermonuclear fusion. Fusion crust and a reddish or oxidizedOxidation and reduction together are called redox (reduction and oxidation) and generally characterized by the transfer of electrons between chemical species, like molecules, atoms or ions, where one species undergoes oxidation, a loss of electrons,  while another species undergoes reduction, a gain of electrons. This transfer of electrons between reactants desert varnish exterior.
• Regmaglypts: Meteorites, both iron and stone, can have regmaglypts, or “thumbprints”. These are depressions, scoops, and ridges on the exterior of the stone caused by ablationGradual removal of the successive surface layers of a material through various processes. • The gradual removal and loss of meteoritic material by heating and vaporization as the meteoroid experiences frictional melting during its passage through the atmosphere. The resulting plasma ablates the meteor and, in cases where a meteor as the meteoroidSmall rocky or metallic object in orbit around the Sun (or another star). enters our atmosphere. Material melts away from the meteorite and “burns off” leaving these thumbprinted like surface.
• Streak Test: The streak test is used to rule out magnetite or hematite which will leave a streak on the non-glazed side of a bathroom tile. Most hunters I know don’t rely on this method, but have used it to identify some meteorwrongs. The logic is that meteorites don’t leave streaks, but this is sometimes unreliable because meteorites contain iron, and will oxidize. This oxidationOxidation and reduction together are called redox (reduction and oxidation) and generally characterized by the transfer of electrons between chemical species, like molecules, atoms or ions, where one species undergoes oxidation, a loss of electrons,  while another species undergoes reduction, a gain of electrons. This transfer of electrons between reactants will leave a “rusty” streak on the tile.
• Windowing: Meteorite hunters will typically carry a piece of very course grit sand paper or a small pocket file in the event they find a meteorite. This aids in identifying possible meteorites when you sand or file a small “window” on an inconspicuous surface of the stone, exposing the interior. You’re looking for two things. ChondrulesRoughly spherical aggregate of coarse crystals formed from the rapid cooling and solidification of a melt at  ~1400 ° C. Large numbers of chondrules are found in all chondrites except for the CI group of carbonaceous chondrites. Chondrules are typically 0.5-2 mm in diameter and are usually composed of olivine, and iron. 90% of stone meteorites are classified as chondritesChondrites are the most common meteorites accounting for ~84% of falls. Chondrites are comprised mostly of Fe- and Mg-bearing silicate minerals (found in both chondrules and fine grained matrix), reduced Fe/Ni metal (found in various states like large blebs, small grains and/or even chondrule rims), and various refractory inclusions (such. Chondrites are named for their chondrules (little spherules a few milimeters in diameter, with the matrixFine grained primary and silicate-rich material in chondrites that surrounds chondrules, refractory inclusions (like CAIs), breccia clasts and other constituents. of the stone). Iron should also be visible as metal bits or flecks inside the stone too. Also, you needn’t worry about damaging the stone. Just find an inconspicuous place to file down to view the interior. It’s common practice to identify a stone as a meteorite. One word of caution, if the meteorite is heavily regmaglypted, do not file or break off a piece. Keep it whole and show it to someone with experience in handling meteorites.
• Visual Examination & ID: Carry with you a 10X jeweler’s loupe. For most treasure hunters this is a common tool in their tool bag. Use the loupe to look for chondrules and the iron flecks within the stone. Use it to examine the exterior of the stone looking for signs of fusion crust. Also look for olivineGroup of silicate minerals, (Mg,Fe)2SiO4, with the compositional endpoints of forsterite (Mg2SiO4) and fayalite (Fe2SiO4). Olivine is commonly found in all chondrites within both the matrix and chondrules, achondrites including most primitive achondrites and some evolved achondrites, in pallasites as large yellow-green crystals (brown when terrestrialized), in the silicate portion crystals. Many meteorites may have visible greenish colored olivine crystals within the matrix of the stone.

If you have found a rock that meets all of the above criteria. you MIGHT have a meteorite! It’s still a good idea to have your rock identified by an experienced collector, hunter, or scientist familiar with meteorites. Do NOT take it to a geologist. Most geologists are not trained in meteorites. Let’s put that statement in perspective. Would you take your car to a brake specialist to fix the transmission? Just because someone works with and studies rocks, does not mean they know anything about meteorites.

Meteorites are rare, some more rare in fact than gold or diamonds. But they are found in every state of the USA, and on every continent on our planetThe term "planet" originally comes from the Greek word for "wanderer" since these objects were seen to move in the sky independently from the background of fixed stars that moved together through the seasons. The IAU last defined the term planet in 2006, however the new definition has remained controversial.. As of this writing some 50,000 plus meteorites have been found, classified and cataloged throughout the world.

If you have a question or think your “hot rock” might be a meteorite. Feel free to email us in focus and sunlit pictures for evaluation.