Rock Identifier
Firewood (Wood Log) (Lignum (Plant tissue composed of cellulose and lignin)) — Organic (Non-geological)
Organic (Non-geological)

Firewood (Wood Log)

Lignum (Plant tissue composed of cellulose and lignin)

Hardness: Soft to hard depending on species (Janka scale); Color: Brown to tan bark with lighter interior; Luster: Dull/Matte; Structure: Fibrous cellular matrix; Cleavage: Splintery fracture along grain; Specific Gravity: 0.4 - 0.9.

Hardness
Soft to hard depending on species (Janka scale)
Color
Brown to tan bark with lighter interior
Luster
Dull/Matte
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Physical properties

Hardness: Soft to hard depending on species (Janka scale); Color: Brown to tan bark with lighter interior; Luster: Dull/Matte; Structure: Fibrous cellular matrix; Cleavage: Splintery fracture along grain; Specific Gravity: 0.4 - 0.9.

Formation & geological history

Biological formation through photosynthesis and secondary xylem growth in perennial woody plants. Ages vary based on harvest time, typically 20-100 years for firewood-sized logs.

Uses & applications

Primary use as fuel for heating and cooking; also used in construction (lumber), paper pulp, and decorative rustic furniture.

Geological facts

Wood is a carbon-neutral fuel source if managed sustainably. The bark protects the tree from pathogens and moisture loss while the interior provides structural support.

Field identification & locations

Identified by presence of bark, growth rings, and fibrous texture. Commonly found in forested areas or woodlots. Collectors may value petrified versions (wood turned to stone), but raw logs are common utility items.

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