The rare CR2 group of stone meteorites is represented by about 160 different examples, over half of which were found in Antartica and are, therefore, not available to collectors. CR2s are ancient carbonaceous chondrites and the “R” in this sub-group is derived from the name of the historic 1824 witnessed fall in Renazzo, Italy.
In a 1991 research paper, Weisberg and Prinz reported that the phyllosilicates and carbonates seen CRs are different from those found in all other meteorites. In 1993, Buseck and Hsu noted that ” … unique to the CRs also occurs as rims surrounding curved, unbroken surfaces of chondrules.” And the chondrules are marvelous in this end cut with polished face: most of them almost perfectly spherical, densely-packed, and of varying size and color. The exterior, unprepared face is almost entirely covered by remnant fusion crust and weathering cracks are visible. This end cut represents a substantial portion of one of only eight stones that are known to exist. Found in 2000, near the town of Zagora, the stones fell within a small strewnfield about 1.5 km in length.
The matrix of carbonaceous chondrites has been changed by the presence of water — described as “aqueous alteration” in scientific terms — and that alteration likely occurred on the parent body (asteroid). CR2s show a particularly high incidence of hydrated matrices (up to 50% by volume). Some scientists believe that, by carrying water and other materials here, carbonaceous chondrites similar to NWA 1180 may have played a part in the evolution of life on Earth.