isotope
12C
Stable, the standard against which all atomic masses are measured. 98.93% of natural carbon.
“All life is woven from a single thread of six protons.”
CO2 · 412 ppm
Atmosphere
Carbon begins as breath. Suspended in the troposphere as carbon dioxide, each molecule traces a slow ellipse through the planet's thermal currents before condensing into leaf, into wood, into coal, into diamond.
isotope
13C
Magnetically active, the silent narrator of every NMR spectrum. 1.07% abundance.
isotope
14C
The clock of the dead — its slow decay calibrates archaeology.
measurement
0
Atmospheric concentration in parts per million, May 2026 — Mauna Loa.
“Six atoms in a ring, repeating without end — the geometry of all things stable.”
sp2 · planar trigonal · ρ 2.267 g/cm³
Graphite
Layered sheets of hexagonal carbon, bound covalently within each plane and held weakly between them by van der Waals whisper. The pencil's mark is the residue of those whispers letting go.
layer · 001
Basal Plane
Bond length 1.42 Å. Each carbon shares electrons with three neighbors in a delocalized π-cloud.
interlayer
3.35 Å
The vertical distance between sheets — wide enough for sheets to slide, narrow enough to hold.
stacking
ABA
Bernal stacking — the canonical configuration in which alternate sheets register exactly above one another.
conductivity
0
In-plane electrical conductivity, S/cm. Across planes, the figure collapses by three orders of magnitude.
use · graphology
2H
Pencil grade: a balanced ratio of graphite to clay. The streak is Bernal stacking dismantled by friction.
thermal
3823 K
Sublimation point. Graphite refuses to liquefy at standard pressure — it simply ascends.
“What is a diamond, but graphite that has remembered how to refuse light?”
sp3 · tetrahedral · Fd-3m · 3.515 g/cm³
Diamond
Under 45 kilobars and 1300 K — the conditions of the lower mantle — carbon abandons its layered laziness. Each atom binds covalently to four neighbors at perfect 109.47° angles. The result is the hardest natural substance.
hardness
0
Mohs scale. Diamond defines the upper bound. Nothing in the mineral kingdom scratches it but itself.
refractive index
0
Light slows by more than half on entry. The internal reflections produce the cut diamond's celebrated fire.
thermal conductivity
0
Watts per meter-kelvin — the highest of any natural material, five times that of copper.
bond length
0
Carbon-carbon σ-bond, in ångströms. Slightly longer than graphite, dramatically stiffer.
band gap
0
Wide-gap insulator at room temperature; the visible spectrum passes through unobstructed.
origin
150 km
Typical depth of formation in cratonic lithosphere. Most diamonds are older than the oldest fossils.
“Sixty atoms folded into a soccer ball — discovered in soot, named for an architect.”
C60 · Ih symmetry · 720.66 g/mol
Fullerene
Twelve pentagons and twenty hexagons stitched into a closed cage of perfect icosahedral symmetry. Synthesized in 1985 by vaporizing graphite into helium — a discovery that opened the third dimension of carbon's possibility.
vertices
60
One carbon at each vertex of the truncated icosahedron.
edges
90
Bonds — 60 single, 30 double — distributed along pentagon-hexagon and hexagon-hexagon seams.
faces
32
12 pentagons (the "defects" that close the cage) and 20 hexagons.
diameter
7.1 Å
Outer cage. The interior cavity (5 Å) is large enough to enclose a single helium atom.
discovered
1985
Kroto, Curl, and Smalley at Rice University. Nobel Prize, Chemistry, 1996.
named for
R. B. Fuller
Inventor of the geodesic dome — the architectural cousin of the buckminsterfullerene cage.
“One atom thick. Two hundred times stronger than steel. Almost transparent. Almost nothing.”
C2 · monolayer · 0.345 nm
Graphene
A single sheet of graphite, isolated in 2004 with adhesive tape and the patience of two physicists in Manchester.
Mechanically the strongest material ever measured. Electrically a zero-gap semiconductor in which charge carriers behave as massless Dirac fermions.
It is the limit-case of carbon — a two-dimensional crystal that should not, according to the Mermin-Wagner theorem, exist at finite temperature.
And yet.
0
atom thick
0
× steel
0
% transparent
0
isolated