Tetragonal

4/m 2/m 2/m (D4h)

三轴垂直，两轴等长 (a = b ≠ c, α = β = γ = 90°)

四方晶系具有三条互相垂直的晶轴，其中两条等长。晶体常呈细长柱状或双锥形态。典型矿物有锆石、金红石、锡石和维苏威石等。

The tetragonal crystal system has three mutually perpendicular axes, with two of equal length and one different (a = b ≠ c, all at 90°). This creates crystals with a square cross-section — elongated or compressed cubes. About 7% of known minerals crystallize in this system. Tetragonal symmetry sits between the high symmetry of cubic and the lower symmetry of orthorhombic, producing elegant prismatic crystals with distinctive four-fold symmetry.

Symmetry

Tetragonal crystals have one four-fold rotation axis (the c-axis) and may have additional two-fold axes and mirror planes. The square cross-section (a = b) with a different c-axis length means crystals look the same after 90° rotation around the c-axis but different if rotated around a or b. The system contains 7 crystal classes. Common crystal forms include tetragonal prisms {100} and {110}, dipyramids, and the distinctive square outline visible in cross-section. Many tetragonal minerals form stubby to elongate prismatic crystals with square or octagonal outlines.

著名矿物

Zircon (ZrSiO₄) is the most famous tetragonal mineral — the oldest known material on Earth, with crystals from Western Australia dated at 4.4 billion years. Rutile (TiO₂) forms slender tetragonal prisms that often penetrate quartz crystals as golden needle-like inclusions. Cassiterite (SnO₂), the primary tin ore, forms distinctive twinned tetragonal crystals. Wulfenite (PbMoO₄) is prized by collectors for its thin, square tabular crystals in vivid orange and yellow. Scapolite forms columnar tetragonal crystals and is used as a gemstone in yellow and purple varieties.

矿物 (4)

Zircon

ZrSiO4

09 Silicates

Cassiterite

SnO2

04 Oxides and Hydroxides

Chalcopyrite

CuFeS2

02 Sulfides and Sulfosalts

Rutile

TiO2

04 Oxides and Hydroxides

常见问题

What is the Tetragonal crystal system?
四方晶系具有三条互相垂直的晶轴，其中两条等长。晶体常呈细长柱状或双锥形态。典型矿物有锆石、金红石、锡石和维苏威石等。
What minerals crystallize in the Tetragonal system?
There are 4 minerals that crystallize in the Tetragonal crystal system on MineralFYI.
What symmetry does the Tetragonal system have?
The Tetragonal crystal system has 4/m 2/m 2/m (D4h) symmetry.
What are the axes of the Tetragonal crystal system?
The Tetragonal system is characterized by 三轴垂直，两轴等长 (a = b ≠ c, α = β = γ = 90°).