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#Introduction  Rocks are the primary source of all plant nutrients, except nitrogen. These nutrients are bound into a variety of crystalline structures (minerals). Minerals are either formed during rock formation from magma (primary mineral) or formed during soil formation (secondary minerals). Secondary minerals are formed when the local soil solution is saturated in respect to that mineral. In contrast to secondary minerals, primary minerals are formed in the earth mantle at high temperature and pressure. At the earth surface these minerals may be thermodynamically unstable. Here, in interaction with water, they either dissolve completely (congruent dissolution) or dissolve partly, leaving a solid residue like clay minerals (incongruent dissolution). This dissolution process is extremely slow for most minerals. It has been estimated that it takes more than 30 million years to dissolve a 1 mm diameter quartz grain under natural soil conditions Lasaga 1984. (\cite{Lasaga_1984}).  Nonetheless, soil mineral weathering provides an essential input of plant nutrients into ecosystems, avoiding or delaying nutrient limitations\cite{chadwick_changing_1999}. limitations (\cite{chadwick_changing_1999}).  In addition, mineral weathering produces cations that counteract soil acidification, thereby improving the availability of most plant nutrients\cite{van_Breemen_1983}. nutrients (\cite{van_Breemen_1983}).  Also clays are formed as a weathering product of feldspars and micas\cite{Oades_1988}. micas (\cite{Oades_1988}).  Clay particles contribute, with their negative charged surfaces, to the cation exchange capacity (CEC) of the soil, reducing the leaching of positively charged nutrients like K+ and NH4+. Clay content correlates positively with water holding capacity and soil organic matter (SOM) content\cite{Sollins_1996}. content (\cite{Sollins_1996}).  Moreover, the weathering of Ca- and Mg-silicate minerals play a central role in the global carbon cycle. The Ca and Mg, released by the weathering process, will be locked up as carbonates in marine sediments\cite{Sundquist_1985}. sediments (\cite{Sundquist_1985}).  On the long-term, atmospheric CO2 is regulated by the weathering rates of these minerals, which is influenced by climate and mountain uplift Berner 2003 Raymo 1992. uplift\cite{Berner_2003}\cite{Raymo_1992}.  The vast amounts of nutrients locked in soil minerals has triggered, nearly 100 years ago, the question if plants actively enter this potential nutrient source \cite{HALEY_1923}\cite{TURK_1919}. Five decennia later, studies appear on the role of microorganisms, including mycorrhizal fungi, in mineral weathering\cite{WEBLEY_1963}\cite{DUFF_1963}\cite{Sperber_1958}\cite{Boyle_1967}\cite{Boyle_1973}. More recently, a publication with the provocative title Rock eating fungi appeared in Nature\cite{Jongmans_1997}. This publication presented evidence of, presumably mycorrhizal, fungal hyphae drilling their way (chemically and/or physically) into feldspar grains. This paper initiated renewed interest into the topic. A series of reviews has been published since then, covering the research up to 2009\cite{Finlay_2009}\cite{Hoffland_2004}\cite{Landeweert_2001}.