Factors controlling growth of modern tufa: results of a field experiment - Tufas and Speleothems: Unravelling the Microbial and Physical Controls - page 170

Fig. 22. (a, b) Highly elongated crystals building fans formed on limestone (a) and copper (b) tablets between
November 2002 and March 2003; (c) fans showing undulose extinction, the same sample as in a, crossed nicols;
(d, e) highly elongated crystals building fans, d - parallel nicols, e - crossed nicols, tufa formed between June and
October 2003, (f ) highly elongated crystals, tufa formed on Cu tablet between August 2002 and October 2003, dark
laminae visible in a - c originated due to increased surface run-off during autumn rains; all samples from L ´ ˇ ky E point,
a - e - thin sections, f - SEM image.

on the textures of tufa deposited in these variable
conditions.
The phenomenon that copper prevents algal
colonization by being toxic to algae (e.g. Anagdos-
tidis & Roussomoustakai 1988; Gorbushina &
Krumbain 2000, fig. 2) was previously employed
in several experiments with growth of tufa and

travertine. Chafetz et al. (1991a) regarded calcite
deposited directly on copper as purely inorganic in
origin. Emeis et al. (1987) did not notice calcium
carbonate deposition on copper sponge immersed
in tufa-depositing water in the Plitvice National
Park, Croatia. Similarly, no tufa was deposited
on copper plates installed in some hard-water