Yes.
Triclinic crystals are usually flat with sharp edges though they don't have right angles.
ex. feldspar
A triclinic crystal system has three unequal crystallographic axes that intersect at oblique angles.
Geologists classify crystal structures based on the arrangement of atoms within the crystal lattice, the symmetry of the crystal, and the types of bonds between atoms. Common crystal structures include cubic, tetragonal, orthorhombic, monoclinic, and triclinic structures.
The crystalline structure of talc can be monoclinic or triclinic. Monoclinic crystals are rectangular prisms with a parallelogram as the base. Triclinic crystals have no mirror planes and little symmetry. In layman's terms, the crystal structure of talc is pretty irregular and haphazard, giving it a rough appearance.
Six crystal classes are known.
Fluorite belongs to the same crystal system as salt - the cubic (also known as the isometric) crystal system.
feldspar
plagioclase, microcline, rhodonite, turquoise, wollastonite, amblygonite, and many more.
A triclinic crystal system has three unequal crystallographic axes that intersect at oblique angles.
Triclinic.
Mineral crystals can appear in any of the six crystal systems (cubic, tetragonal, orthorhombic, monoclinic, triclinic, hexagonal) depending on their internal atomic arrangement. The structure and symmetry of a mineral crystal is determined by factors such as its chemical composition and how the atoms are arranged within the crystal lattice.
An aheylite is a pale blue or green triclinic mineral.
Minerals crystals are divided into six systems depending on the relationships of length of axes and angles between axes. The six mineral crystal systems are: cubic, hexagonal, trigonal, tetragonal, orthorhombic, triclinic, and monoclinic.
Aenigmatite is a mineral of sodium, iron and titanium, which forms brown to black triclinic lamellar crystals.
Atoms within a mineral are arranged into an orderly geometric spatial arrangement known as crystal structure. There are 14 basic crystal lattices (refered to as the Bravais lattices) which fit into one of 7 crystal system (triclinic, monoclinic, orthorhombic, tetragonal, rhombohedral, hexagonal and cubic) and all observed minerals fit into one crystal lattice and one crystal system. Diamond on the other hand is an allotrope of carbon arranged into an isometric hexoctahedral (Cubic-type) crystal system.
Geologists classify crystal structures based on the arrangement of atoms within the crystal lattice, the symmetry of the crystal, and the types of bonds between atoms. Common crystal structures include cubic, tetragonal, orthorhombic, monoclinic, and triclinic structures.
mineral
The color left on a streak plate when the mineral is scratched on the surface of the plate. Different minerals have different streak colors. The mineral is tested for hardness to see where it lies on the Mohs scale. The crystal structure (othorhombic, tetragonal, triclinic, isometric, monoclinic, or trigonal), will help identify the mineral. Different minerals have different densities and weights.