How can stones be cleaned of lichen growth?

We live in Colorado on 6 acres with lots of local sand (http://maplered.com) Stone (http://g603.net) . My wife has the
idea to collect this Stone (http://g603.net) and (http://maplered.com) arrange with a local Stone (http://g603.net) mason to lay a
Stone (http://g603.net) floor and (http://maplered.com) build fireplace out of this local rock.  This seems very
labor intensive.  Do you think we can find someone to do it.  How is
sand (http://maplered.com) Stone (http://g603.net) for interior use, especially a floor.  Will it show stains, can it
be adequately sealed?  Are airborne silicates a concern?  How can Stone (http://g603.net) s be
cleaned of lichen growth?

Lou, Durango