Microcrystalline silica materials
Agate, jasper and commercial pattern names are useful reading paths, not separate species in every case. Grape agate is cross-referenced to botryoidal quartz.
Keep each chapter’s scientific identity: a family, species, variety, trade label, rock and fossil are different kinds of names.
Mineral variety
Agate draws attention through bands, repeated curves and changing translucence. It belongs with chalcedony: silica-rich material whose crystals are far smaller than the large points associated with rock crystal.
Shannon Heinle · CC0 · Display crop
Mineral variety
Carnelian is the warm orange-to-reddish member of the chalcedony collection. A smooth polish and light passing through a thinner edge often reveal its character more clearly than a distant photograph.
Shannon Heinle · CC0 · Display crop
Rock / aggregate
Red jasper is an opaque, silica-rich material often chosen for its earthy red color and individual pattern. It is a useful contrast to the transparency of clear quartz and the soft translucence of carnelian.
Darla Sondrol · CC0 · Display crop
Mineral variety
Moss agate contains branching or moss-like mineral patterns in chalcedony. These can be green, dark or otherwise varied, so the name describes an appearance rather than one fixed color.
Shannon Heinle · CC0 · Display crop
Mineral variety
Blue lace agate is a pale blue-and-white banded chalcedony trade variety. Its fine curved lines work especially well across a broad polished surface.
Stephanie Clifford from Arlington, VA, USA · CC BY 2.0 · Display crop
Mineral variety
Chrysoprase is a green chalcedony variety, often with an inviting apple-green translucence. Rounded polished forms show its color without needing the reflections of a faceted gem.
Xth-Floor · CC BY-SA 3.0 · Display crop
Gem material
Bloodstone pairs a dark green host with small red to orange mineral markings. Its name describes a visual pattern and a long cultural history, rather than any relationship to human blood.
Ra'ike (see also: de:Benutzer:Ra'ike) · CC BY-SA 3.0 · Display crop
Gem material
Black onyx is a familiar jewelry trade name for dark chalcedony. Its clean reflective surface can look very different from the visibly banded material behind the geological name onyx.
Robert M. Lavinsky · CC BY-SA 3.0 · Display crop
Mineral variety
Blue chalcedony has a soft translucent appearance that is different from the clear transparency of a single quartz crystal. Broad polished surfaces invite a slower look at clouds and subtle color.
Jamescarolinewiki · CC BY-SA 4.0 · Display crop
Orbicular silica-rich material / trade name
Orbicular patterns give this commercial material its appeal. The name does not establish an ocean formation process or a documented Madagascar origin for every marketed piece.
Vassil · Public domain · Display crop
Patterned silica-rich material / trade name
Landscape-like bands and patches are visual associations, not pictures of a real landscape. Composition and locality can vary; the trade label is broader than a mineral species.
Deidre Woollard · CC BY 2.0 · Display crop
Multicolored silica-rich material / trade name
Several earthy colors and broad patterns distinguish the trade appearance. The label does not fix one chemical composition, locality or mineral assemblage.
James St. John · CC BY 2.0 · Display crop
Plume-like chalcedony / trade name
Pale plume-like patterns resemble blossoms. They are mineral textures, not preserved flowers; the commercial name does not identify every inclusion or prove one mine source.
James St. John · CC BY 2.0 · Display crop
Botryoidal quartz / misleading trade name
Grape-like spheres describe the habit. Material sold under this name may show crystalline quartz surfaces and is not automatically banded chalcedony merely because “agate” appears in its name.
Didier Descouens · CC BY-SA 4.0 · Display crop
Banded chalcedony / locality trade name
Fine gray, white or brown bands are typical in the trade. An attractive banded agate still needs a documented record before Botswana can be stated as its origin.
Lech Darski · CC BY-SA 4.0 · Display crop
Patterned chalcedony / trade name
Complex lace-like bands create a busy, flowing pattern. Pattern names are useful for browsing but do not replace a material identification or a supplier’s locality record.
James St. John · CC BY 2.0 · Display crop
Dendritic chalcedony / trade name
Branching mineral inclusions resemble plants but are not plant fossils. Many commercial dendritic materials have little banding, so “dendritic chalcedony” can be the clearer description.
峠 武宏 · CC BY-SA 3.0 · Display crop
Iridescent chalcedony variety
Iridescence associated with layered botryoidal structures distinguishes fire agate. It is not simply any orange-red agate, and its effect is different from opal play-of-color.
Brocken Inaglory · CC BY-SA 3.0 · Display crop
Layered sard and contrasting chalcedony
Sardonyx combines sard-colored layers with contrasting pale layers. It is not a separate species; dyed banded material must be distinguished from its untreated appearance.
Warclachaja · CC BY-SA 4.0 · Display crop