Mineralogy of Halides, Carbonates, and Sulfites

Introduction to Halides, Carbonates, and Sulfites

Halides, carbonates, and sulfites (not “sulfides”) are studied together because most of them form in similar environments and are chemically deposited from water. Being connected to halides and carbonates, sulfites will let you easily remember how to differentiate them from sulfides.

Halides, carbonates, and sulfites have many similar physical properties. Most of the minerals are light colored (colorless or white, gray, ivory, yellow, orange), transparent to translucent, with vitreous luster, low density, and low (2 for gypsum) to medium (4.5 for magnesite) hardness, making differentiation between mineral species quite challenging. Also, minerals occur in various crystal forms: form perfectly symmetrical, well-formed crystals to nodular, botryoidal, stalactitic, columnar, fibrous, granular, and massive aggregates, with a common crystal twinning.

Evaporite Minerals

Before learning each class separately, we want to pay attention to evaporites. These are salt rocks originally precipitated from a saturated surface or near-surface brine in hydrologies driven by solar evaporation (Warren, 2016). [The world salt used to mark the type of chemical compound, not only common table salt. Hydrologies are different water reservoirs like seas, lakes, rivers, and their isolated parts].

Many halides, carbonates, and