It is thrilling to be surprised by yet another micrometeorite! Most of these beautiful emissaries from the depths of outer space fit quite nicely into the categories of micrometeorites as defined by the scientific community. However, every once in a while, I encounter strange particles that disrupt the current lexicon.
It is therefore my pleasure to introduce to you a new micrometeorite that was found recently, during Field Search #1071. NMM 3222 falls between chairs, in that it is a strange transitional form that has characteristics of both barred olivine (BO) and porphyritic olivine (PO) type micrometeorites.
Measuring 0.3 mm, NMM 3222 initially appears average. At first glance, the parallel stripes indicate a BO-type particle, which is the most common type of micrometeorite. However further inspection reveals pyramidal crystals erupting from the deep, which is a typical feature of PO-type particles. How delightful!
We see here, it is possible to have two seemingly distinct types combined in one spherule (or spherical particle). While this phenomenon has been observed in other particles, the different types occupied different parts of the micrometeorite. For example, NMM 960 is a droplet that appears to be two different particles that were fused into one; The spherical part is a glass (V) type and the elongated part is a cryptocrystalline (CC) type. But, here we see a spherule — one particle that has achieved a spherical form and lacks any separation between the different types.