bakri gismu

x1 is a quantity of/contains/is made of chalk from source x2 in form x3.

See also pinsi, blabi, jilka.

In notes:

blabi
x1 is white/very-light colored [color adjective].
jilka
x1 is a quantity of/contains/is made of alkali/base of composition including x2.
pinsi
x1 is a pencil/crayon/stylus applying lead/marking material x2, frame/support [of material] x3.
bogjinme
x1 is calcium.
digyligykamju
k1 is a dropstone/stalagmite/stalactite/icicle/rusticle of material k2=s2=d2.
selbakri
x2=b1 is chalk from source x1=b2 in form x3=b3.
terbakri
x3=b1 is chalk from source x2=b2 in form x1=b3.