Sedimentary rocks and minerals
Grains, cements and bedding. These are the rocks that record water, wind, life and time without metamorphosing any of it away.
| Sheet | Name | Formula | Mohs | |
|---|---|---|---|---|
| ST-008 Sedimentary | Sandstone砂岩 Sandstone is a photograph of a current. Every grain in it was moved by water or wind, and three measurements taken in the field — grain size, sorting and roundness — tell you how far it trav Hand specimen | Quartz grains (SiO₂) with a cement of silica, calcite, iron oxide or clay | 6–7 for quartz grains; the rock's resistance is set by the cement | |
| ST-009 Sedimentary | Limestone石灰岩 Limestone is the easiest of the common rocks to identify and the hardest to identify well, because one drop of acid answers the first question and leaves every interesting question untouched Hand specimen | CaCO₃, mostly as calcite, with variable clay, silica and magnesium | 3 (calcite controls everything) |
