tizas

Tizas are sticks or blocks made primarily from calcium carbonate that are used for writing or drawing. The term covers several related products, most notably classroom chalk for writing on blackboards and chalks used by artists, as well as climbing chalk made from magnesium carbonate.

In education, tizas are traditionally white or lightly tinted and pressed into uniform sticks. They leave a mark on slate or green boards by scraping against the surface. In art, colored tizas—often referred to as chalks or pastel chalks—are used for drawing and shading. These artist’s tizas are typically pigments bound with a gum, glycerin, or similar binder, producing a soft, blendable texture. A related art product are soft pastels, which are highly pigmented sticks with a binder for smooth application.

Climbing and sports contexts use a different kind of tiza: magnesium carbonate powder or blocks applied to the hands to improve grip by absorbing sweat. This form is not for writing or drawing but is widely used by climbers and weightlifters.

Composition and properties vary by type. Classroom chalk is mainly CaCO3 with minor binders and colorants; colored chalks and pastels add pigments and binders. Chalk sticks used for climbing are purer magnesium carbonate. Chalks are known for being inexpensive and readily available, but their dust can be messy and, in enclosed spaces, irritating to the respiratory tract.

In summary, tizas encompass chalks for writing, artist’s chalks for drawing, and magnesium carbonate chalks for grip, all sharing a common origin in chalky minerals. See also chalk, pastels, and climbing chalk.