An evolutionary system of mineralogy. Part II: Interstellar and solar nebula primary condensation mineralogy (>4.565 Ga)

Abstract

The evolutionary system of mineralogy relies on varied physical and chemical attributes, including trace elements, isotopes, solid and fluid inclusions, and other information-rich characteristics, to understand processes of mineral formation and to place natural condensed phases in the deep-time context of planetary evolution. Part I of this system reviewed the earliest refractory phases that condense at T > 1000 K within the turbulent expanding and cooling atmospheres of highly evolved stars. Part II considers the subsequent formation of primary crystalline and amorphous phases by condensation in three distinct mineral-forming environments, each of which increased mineralogical diversity and distribution prior to the accretion of planetesimals >4.5 billion years ago.

Interstellar molecular solids: (1)Varied crystalline and amorphous molecular solids containing primarily H, C, O, and N are observed to condense in cold, dense molecular clouds in the interstellar medium (10 < T < 20 K; P < 10^-13 atm). With the possible exception of some nanoscale organic condensates preserved in carbonaceous meteorites, the existence of these phases is documented primarily by telescopic observations of absorption and emission spectra of interstellar molecules in radio, microwave, or infrared wavelengths.

Nebular and circumstellar ice: (2)Evidence from infrared observations and laboratory experiments suggest that cubic H₂O ("cubic ice") condenses as thin crystalline mantles on oxide and silicate dust grains in cool, distant nebular and circumstellar regions where T ~100 K.

Primary condensed phases of the inner solar nebula: (3)The earliest phase of nebular mineralogy saw the formation of primary refractory minerals that solidified through high-temperature condensation (1100 < T < 1800 K; 10^-6 < P < 10^-2 atm) in the solar nebula more than 4.565 billion years ago. These earliest mineral phases originating in our solar system formed prior to the accretion of planetesimals and are preserved in calcium-aluminum-rich inclusions, ultra-refractory inclusions, and amoeboid olivine aggregates.

Keywords: Classification; chondrite meteorites; condensation; interstellar mineralogy; mineral evolution; natural kinds; nebular mineralogy; vapor deposition.

FIGURE 1.

The temperature, pressure, and compositional characteristics of primary interstellar and solar nebular condensates result in a distinctive second phase of the evolutionary system of mineralogy. (a) These minerals formed at a wide range of temperatures via low-pressure (P < 0.01 atm) condensation in interstellar and nebular environments. (b) Interstellar minerals formed primarily from C, H, N, O, and probably S—five of the most abundant elements in the cosmos. (c) Primary minerals in CAIs, URIs, and AOAs formed principally from 16 essential major elements, with important additional contributions from 7 minor elements. (Color online.)

FIGURE 2.

A 2015 Hubble Space Telescope image of a portion of the Eagle Nebula (NGC 6611 and IC 4703), dubbed “The Pillars of Creation,” displays a star-forming region of a dense molecular cloud. The core regions of this structure are cooler areas, dense molecular clouds where molecular solids condense. [Image credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA).] (Color online.)

FIGURE 3.

Components of primitive chondrite meteorites with primary mineral phases include: calcium-aluminum-rich inclusions (CAIs), amoeboid olivine aggregates (AOAs), and ultra-refractory inclusions (URIs). (a) Compact type A CAI from the Adelaide meteorite with primarily melilite and spinel and minor perovskite and fassaite (Ti = red; Ca = green; Al = blue); (b) fluffy type A CAI from the Allende meteorite with melilite, spinel, fassaite, and anorthite (Mg = red; Ca = green; Al = blue); (c) type B CAI from the Allende meteorite with melilite, fassaite, spinel, and anorthite (Mg = red; Ca = green; Al = blue); (d) type C CAI with anorthite, melilite, spinel, and fassaite (Mg = red; Ca = green; Al = blue); (e) forsterite-rich AOA from the Kainsaz meteorite with dominant forsterite plus Fe-Ni metal alloys, fassaite, spinel, and anorthite (Mg = red; Ca = green; Al = blue); (f) URI in matrix from the Allende carbonaceous chondrite. (Image credits: a, b, d, e, courtesy of Alexander Krot, University of Hawaii; c, courtesy of Denton Ebel, American Museum of Natural History; f, courtesy of Chi Ma, Caltech.) (Color online.)

FIGURE 4.

Bipartite force-directed network graph (Morrison et al. 2017) of primary stellar, interstellar, and nebular minerals linked to their modes of paragenesis. Diamond-shaped nodes represent condensed crystalline and amorphous phases [black (C-bearing), green (not C or O), blue (contains O, but not C or Si), and red (contains Si+O)]. Star-shaped nodes represent three types of host stars—asymptotic giant branch stars (AGB), Type II supernovae (SN-II), and classical novae (CNova); the cloud-shaped node represents dense molecular clouds (DMC); and four disk-shaped nodes indicate circumstellar environments, CAIs, AOAs, and URIs. The sizes of nodes correspond to the numbers of links to other nodes. Note that 8 low-temperature phases of the interstellar medium are not linked to 61 high-temperature primary phases of stellar and nebular environments. Network graph developed in collaboration with Anirudh Prabhu. (Color online.)