Tsaoka
Apparence
![](http://178.128.105.246/content-http-upload.wikimedia.org/wikipedia/commons/thumb/d/dd/Colored_chalks_%283391214973%29.jpg/164px-Colored_chalks_%283391214973%29.jpg)
Ny tsaoka dia karazana vatosokay maivana, fotsy na fotsifotsy, malemy, misy hirika maro sy tantera-drano, ary madio saika tsy ahitana afa-tsy karibônetra-na kalsiôma CaCO3 (90 % na mihoatra) sy tanimanga kely na mineraly hafa. Miforona avy amin' ny sisa tavela amin' ny zavamananaina an-dranomasina mafana sy marivo toy ny lomotra planktôna, miampy sombiny miovaova avy amin' ny fôraminifera sy kôkôlita. Miovaova ny hamafiny sy ny firafiny. Matetika dia ahitana tsaoka ny sosona kretasea (avy amin' ny teny latina hoe creta, "tsaoka").