Context : We study the absorption and scattering of X-ray radiation by interstellar dust particles , which allows us to access the physical and chemical properties of dust .
The interstellar dust composition is not well understood , especially on the densest sight lines of the Galactic Plane .
X-rays provide a powerful tool in this study .

Aims : We present newly acquired laboratory measurements of silicate compounds taken at the Soleil synchrotron facility in Paris using the Lucia beamline .
The dust absorption profiles resulting from this campaign were used in this pilot study to model the absorption by interstellar dust along the line of sight of the low-mass X-ray binary ( LMXB ) GX 5-1 .

Methods : The measured laboratory cross-sections were adapted for astrophysical data analysis and the resulting extinction profiles of the Si K-edge were implemented in the SPEX spectral fitting program .
We derive the properties of the interstellar dust along the line of sight by fitting the Si K-edge seen in absorption in the spectrum of GX 5-1 .

Results : We measured the hydrogen column density towards GX 5-1 to be 3.40 \pm 0.1 \times 10 ^ { 22 } \mathrm { cm } ^ { -2 } .
The best fit of the silicon edge in the spectrum of GX 5-1 is obtained by a mixture of olivine and pyroxene .
In this study , our modeling is limited to Si absorption by silicates with different Mg : Fe ratios .
We obtained an abundance of silicon in dust of 4.0 \pm 0.3 \times 10 ^ { -5 } per H atom and a lower limit for total abundance , considering both gas and dust , of > 4.4 \times 10 ^ { -5 } per H atom , which leads to a gas to dust ratio of > 0.22 .
Furthermore , an enhanced scattering feature in the Si K-edge may suggest the presence of large particles along the line of sight .

Conclusions :