  AGB stars are one of the main sources of dust production in the Galaxy.
However, it is not clear what this process looks like and where the dust is
condensing in the circumstellar environment. By characterizing the location of
the dust and the molecules in the close environment of an AGB star, we aim to
achieve a better understanding the history of the dust formation process. We
observed the carbon star R Scl with the VLTI-MATISSE instrument in L- and
N-bands. The high angular resolution of the VLTI observations, combined with a
large uv-plane coverage allowed us to use image reconstruction methods. To
constrain the dust and molecules' location, we used two different methods: MIRA
image reconstruction and the 1D code RHAPSODY. We found evidence of C2H2 and
HCN molecules between 1 and 3.4 Rstar which is much closer to the star than the
location of the dust (between 3.8 and 17.0 Rstar). We also estimated a
mass-loss rate of 1.2+-0.4x10-6 Msun per yr. In the meantime, we confirmed the
previously published characteristics of a thin dust shell, composed of
amorphous carbon (amC) and silicon carbide (SiC). However, no clear SiC feature
has been detected in the MATISSE visibilities. This might be caused by
molecular absorption that can affect the shape of the SiC band at 11.3 micron.
The appearance of the molecular shells is in good agreement with predictions
from dynamical atmosphere models. For the first time, we co-located dust and
molecules in the environment of an AGB star. We confirm that the molecules are
located closer to the star than the dust. The MIRA images unveil the presence
of a clumpy environment in the fuzzy emission region beyond 4.0 Rstar.
Furthermore, with the available dynamic range and angular resolution, we did
not detect the presence of a binary companion. Additional observations
combining MATISSE and SAM-VISIR instrument should enable this detection in
future studies.
