MINERALOGY — Identify the most familiar halide mineral. Within the halide group of minerals (salts of halogens), which is the most well-known and widely occurring example?

Introduction / Context:
Minerals are grouped by their dominant anion. Halides contain halogen anions such as Cl⁻ and F⁻. Recognizing key examples helps in basic mineral identification and understanding depositional environments.

Given Data / Assumptions:

• The question asks for the most familiar halide mineral.
• Options include minerals from different classes.
• Familiarity refers to abundance, usage, and textbook prominence.

Concept / Approach:
Halite (NaCl) is rock salt, forming by evaporation of saline waters in arid basins. It is ubiquitous in stratified evaporite deposits and is economically important (salt). Other classes: Pyrite (FeS₂) is a sulfide; Galena (PbS) is also a sulfide; Hematite (Fe₂O₃) is an oxide; Fluorite (CaF₂) is indeed a halide but is less abundant and less universally known than halite in basic curricula.

Step-by-Step Solution:
Identify halide minerals among options: Halite (Cl⁻), Fluorite (F⁻).Compare prominence and commonness: Halite is the archetypal halide (rock salt).Exclude non-halides: Pyrite and Galena (sulfides), Hematite (oxide).Select Halite.

Verification / Alternative check:
Introductory geology and geochemistry texts list halite first when introducing halide minerals, emphasizing its economic significance and diagnostic properties (salty taste, cubic cleavage).

Why Other Options Are Wrong:
Pyrite — sulfide, not halide.Galena — sulfide, not halide.Hematite — oxide; major iron ore but not a halide.Fluorite — halide but not as ubiquitous as halite in basic examples.

Common Pitfalls:
Assuming all shiny or common ores are halides. Always classify by anion group first.

Final Answer:
Halite