Tufa

About it

Soft, spongy calcite rock deposited around cool springs and in lakes, often coating moss, leaves, and twigs. Mono Lake, California, has famous tufa towers; not to be confused with tuff, which is volcanic.

Type

Rock (sedimentary)

Group

Sedimentary (chemical)

Lustre

dull, earthy

Colours

white, cream, tan, grey

Transparency

opaque

Typical values: real specimens vary. For more, see mindat.org.